WORLD WIDE WEB

WORLD WIDE WEB

The World Wide Web ("WWW" or simply the "Web") is a global information medium which users can read and write via computers connected to the Internet. The term is often mistakenly used as a synonym for the Internet itself, but the Web is a service that operates over the Internet, just as e-mail also does. The history of the Internet dates back significantly further than that of the World Wide Web.

Sir Tim Berners-Lee is a British computer scientist. He was born in London, and his parents were early computer scientists, working on one of the earliest computers.Growing up, Sir Tim was interested in trains and had a model railway in his bedroom. He recalls:

“I made some electronic gadgets to control the trains. Then I ended up getting more interested in electronics than trains. Later on, when I was in college I made a computer out of an old television set.”

After graduating from Oxford University, Berners-Lee became a software engineer at CERN, the large particle physics laboratory near Geneva, Switzerland. Scientists come from all over the world to use its accelerators, but Sir Tim noticed that they were having difficulty sharing information.

“In those days, there was different information on different computers, but you had to log on to different computers to get at it. Also, sometimes you had to learn a different program on each computer. Often it was just easier to go and ask people when they were having coffee…”, Tim says.

Tim thought he saw a way to solve this problem – one that he could see could also have much broader applications. Already, millions of computers were being connected together through the fast-developing internet and Berners-Lee realised they could share information by exploiting an emerging technology called hypertext.

In March 1989, Tim laid out his vision for what would become the web in a document called “Information Management: A Proposal”. Believe it or not, Tim’s initial proposal was not immediately accepted. In fact, his boss at the time, Mike Sendall, noted the words “Vague but exciting” on the cover. The web was never an official CERN project, but Mike managed to give Tim time to work on it in September 1990. He began work using a NeXT computer, one of Steve Jobs’ early products.

History of the Web

WEB PAGE

A web page or web page is a document commonly written in HyperText Markup Language (HTML) that is accessible through the Internet or other network using an Internet browser. A web page is accessed by entering a URL address and may contain text, graphics, and hyperlinks to other web pages and files. The page you are reading now is an example of a web page.

The first web page was created at CERN by Tim Berners-Lee on August 6, 1991. You can visit and browse the first website and first web page .

This page that you are reading now is an example of an HTML web page and what a typical web page looks like on the Internet. This web page consists of several elements including CSS, images, and JavaScript.

Although the body of a web page is created using HTML, that HTML code can be created using an HTML editor and written by a human or generated using server-side scripts or other scripts. Typically a web page created by a human ends with a .htm or .html file extension. For example, this page has the file name "webpage.htm". Pages generated by a script can end in .cgi, .php, .pl, and other extensions.

A static web page (sometimes called a flat page/stationary page) is a web page that is delivered to the user exactly as stored, in contrast to dynamic web pages which are generated by a web application.

Consequently, a static web page displays the same information for all users, from all contexts, subject to modern capabilities of a web server to negotiate content-type or language of the document where such versions are available and the server is configured to do so.

Static web pages are often HTML documents stored as files in the file system and made available by the web server over HTTP (nevertheless URLs ending with ".html" are not always static). However, loose interpretations of the term could include web pages stored in a database, and could even include pages formatted using a template and served through an application server, as long as the page served is unchanging and presented essentially as stored.

Static web pages are suitable for the contents that never or rarely need to be updated, though modern static site generators are changing. Maintaining large numbers of static pages as files can be impractical without automated tools, such as Static site generators described in Web template system. Any personalization or interactivity has to run client-side, which is restricting.

Advantages of a static website

• Provide improved security over dynamic websites[1]
• Improved performance for end users compared to dynamic websites[2]
• Fewer or no dependencies on systems such as databases or other application servers

Disadvantages of a static website

• Dynamic functionality has to be added separately

A dynamic web page is a web page that displays different content each time it's viewed. For example, the page may change with the time of day, the user that accesses the webpage, or the type of user interaction. There are two types of dynamic web pages :

CLIENT-SIDE SCRIPTING

Web pages that change in response to an action within that web page, such as a mouse or a keyboard action, use client-side scripting.

Client-side scripts generate client-side content. Client-side content is content that's generated on the user's computer rather than the server. In these cases, the user's web browser would download the web page content from the server, process the code that's embedded in the web page, and then display the updated content to the user.

Scripting languages such as JavaScript and Flash allow a web page to respond to client-side events.

SERVER-SIDE SCRIPTING

Web pages that change when a web page is loaded or visited use server-side scripting. Server-side content is content that's generated when a web page is loaded. For example, login pages, forums, submission forms, and shopping carts, all use server-side scripting since those web pages change according to what is submitted to it.

Scripting languages such as PHP, ASP, ASP.NET, JSP, ColdFusion and Perl allow a web page to respond to submission events.

How web page work

WEB BROWSER

A web browser is a software program that allows a user to locate, access, and display web pages. In common usage, a web browser is usually shortened to "browser." Browsers are used primarily for displaying and accessing websites on the Internet, as well as other content created using Hypertext Markup Language (HTML) and Extensible Markup Language (XML), etc.

Browsers translate web pages and websites delivered using Hypertext Transfer Protocol (HTTP) into human readable content. They also have the ability to display other protocols and prefixes, such as secure HTTP (HTTPS), File Transfer Protocol (FTP), email handling (mailto:), and files (file:). In addition, most browsers also support external plug-ins required to display active content, such as in-page video, audio and Flash content.

A variety of web browsers are available with different features, look-and-feel, and designed to run on different operating systems. Common browsers include Internet Explorer from Microsoft, Firefox from Mozilla, Google Chrome, Safari from Apple, and Opera. All major browsers have mobile versions that are lightweight versions for accessing the web on mobile devices.

Web browsers date back to the late 1980s when an English scientist, Tim Berners-Lee, first developed the ideas that led to the World Wide Web (WWW). This consisted of a series of pages created using the HTML language and joined or linked together with pointers called hyperlinks. 

• In 1993, a new browser known as Mosaic was developed, which soon gained widespread usage due to its graphical-interface capability. Marc Andreesen, a member of the Mosaic development team.
• In 1994 to develop his own commercial browser based on Mosaic. He called it Netscape Navigator, and it quickly captured over 90 percent of the nascent browser market. It soon faced stiff competition .
• In 1995 from Microsoft's Internet Explorer, which was freely bundled with Windows 95 and has been a feature of every version of Windows since that time. It was pointless to buy Navigator when Internet Explorer was free, and as a result, Navigator (and Netscape) were driven into the ground. But while Mosaic an Netscape are no longer around, the age of the browser was launched and continues to this day, as more and more applications move to the web.

Best Web Browser

WEB ADDRESS

Example : https://itstillworks.com/timeout-error-8361586.html

In the earliest days of the Internet, the only way to connect with a remote computer was to provide its unique IP address, a long string of digits such as 165.254.202.218. But in 1983, as the number of computers on the network continued to grow, the University of Wisconsin developed the Domain Name System (DNS), which maps numeric IP addresses to more easily remembered domain names like www.twitter.com .

Website addresses are entered into the address bar of an Internet browser. The browser, if connected to the Internet and configured correctly, has the ability to display the web page presented by the hosting provider. Examples of browsers include Internet Explorer, Firefox, Safari and Google Chrome.

This name translates, through a DNS service, to a unique number called an IP address. This IP address is registered and gets routed through the Internet to a hosting provider. Servers at the hosting provider present the user with the file or web page requested. Errors are presented to the user if the provider has improperly configured the environment or traffic limits have been exceeded.

PROTOCOL

The first section of a URL is called the protocol and is characterized by the letters "http" or "https." This stands for "hypertext transfer protocol," and is the method by which text is transferred from webpage to webpage on the Internet. The "s" at the end indicates that the website you're viewing is on a secure server, making it harder for malicious software or Internet users to illegally access your computer.

DOMAIN NAME 

The second section of a URL is called the domain name, and it follows the protocol. It begins with the letters "www" that stand for "World Wide Web," followed by the website's name. However, the "www" is generally not required to access a site. The domain name is registered with a company that hosts the website and supports its content storage and visitor usage demands.

PATH

The third section of a URL is called the path, and leads users to additional web pages that are linked to or branching off the domain name. The path is also the address of additional pages on the web host's server.

TOP-LEVEL DOMAIN NAME

The top-level domain (TLD) name is composed of the characters at the end of a URL -- generally, either two or three letters. Most URLs end with ".com," which is the most common top-level domain, and any website can use this ending. Other common three-letter TLDs are ".gov," ".edu" and ".mil" for government sites, educational sites and military sites, respectively. Two-letter TLDs are specific to countries, such as ".uk" for the United Kingdom.

DIFFERENT TYPES OF INTERNET CONNECTION, INTERNET SERVICE PROVIDER AND THE INTERNET ADDRESS

INTERNET CONNECTION

There are two types of internet connection which is Dial-up Connection and Broadband intertnet connection/Direct connection.

                 Dial up connection                        

Dial-up has to dial via a phone to connect and its connect to a modem attached to a computer. The advantages of conventional dial-up is easy to setup and use, include inexpensive hardware. Its also more secure because the user not continually connected to the internet, it is much less likely the hackers will gain access to your computer via internet.
But its also has disadvantage which is slow connection speed. The maximum speed is 56Kbps. The telephone line will be tie up while accessing the internet. Lastly its inconvenience because its have to instruct user’s PC to dial up user’s ISP every time when the user wan to check email or view website.

CHARACTERISTIC OF DIAL-UP CONNECTION.

Conventional Dial-up	ISDN(Integrated Service Digital Network)
Slow but cheaper	Faster but pricey
Ties up phone lines	Doesn’t tie up phone line
Relatively secure from hackers	Used by business and individual

 Direct connection used at many home and small business users connect to the internet via high speed broadband internet.PC is continually connected to the Internet. Direct connections are typically broadband and used in home and office. Because you are always connected, it is  important to protect your computer from hackers

DSL	FTTP	Fixed Wireless	Cellular Radio Network	Cable Internet Service	Wi-Fi	Satellite Internet Service
Broadband delivered over telephone lines	Also known as Broadband over Fiber (BoF)	Uses radio transmission towers rather than satellites	Also known as Mobile wireless	widely used home broadband connection	Data is transmitted through radio waves	A satellite dish communicates with a satellite modem
Must be less than 3 miles from a switching station	Uses fiber-optic cable		Access via mobile phone or device		Currently Wi-Fi for short range, but WiMAX may soon be an option
Transmits over telephone lines but does not tie up the line	Delivers over fiber-optic cabling all the way to the building				Both free and fee-based are available
Fast, direct Internet access via standard telephone line	Provide high-speed Internet access to house and business users.	Provides high-speed Internet connections using a dish-shaped antenna to communicate via radio signals.	Offers high-speed Internet connections to devices with built-in compatible technology/ computers with wireless modems.	Provides high-speed Internet access through    the cable television network via a cable modem.	Provide high-speed Internet connections to compatible or properly equipped wireless computers and device.	Provides high-speed Internet connections via satellite.
Requires DSL modem	Fast but expensive	Expected to use WiMAX				More expensive than cable or DSL
Available in urban areas	Available in limited areas	Not available in all areas				Broadband option for rural areas
Example :- Streamyx without WiFi			Example provider:- Celcom, Maxis, DiGi		Example : Streamyx with WiFi

 ISP(Internet Service Provider)

• A company that provides Internet connections and services to individuals and organizations. 
• Providing and maintaining a connection to the Internet
• Support the hardware and software needed to service that connection
• To protect their site and network from external threats such as viruses, hacker attacks and other illegal activities
• Provide 24-hour customer service and technical support
• Example : 

1. ISP: TMNet
2. Products : Streamyx , UniFi, TM Hotspot
3. ISP : Time
4. Product : Time Fibre Home Broadband, Time Broadband
5. ISP: Packet One Network
6. Products : P1
7. ISP : YTL Communications
8. Product : YES

ISP

INTERNET ADDRESS 

INTERNET ADDRESS

IP ADDRESS

• A number that uniquely identifies each computer or device connected to the Internet.
• IP addresses are also referred to as IP numbers and Internet addresses.
• IP address sometimes is called a dotted decimal number or dotted quad.
• Unique
• Global and standardised
• Essential

IP USAGE 

• A way to find specific server or computer on the internet or a network
• Provide identity to a computer in a network
• Identify for a particular device/machine on a particular network
• Allows transfers of files and e-mail

IP STRUCTURE 

• IP addresses usually consists of four groups of number each separated by a period.
• The number in each group is between 0 and 255.
• It is 32 bit long ,each group is 8 bits long
• Commonly written in decimal.
• Written, for example, 128.35.0.72
• These four sections represent the machine itself and the network it is on
• The network portion is assigned.
• The host section is determined by the network administrator

IP VERSION 

IP ADDRESS

IP Version 4 (IPv4)

IPv4

• IPv4 an address consists of 32 bits which limits the address space to 4294967296 (232) possible unique addresses.
• Version 4 of Internet Protocol, the most widely used version of IP.

IP Version 6 (IPv6)

IPv6

• The address size was increased from 32 to 128 bits or 16 octets.
• Provides the potential for a maximum of 2128, or about 3.403×1038 unique addresses.
• Version 6 of  Internet Protocol, has more capabilities than IPv4, including providing for far more IP address.

DOMAIN NAMES AND IP ADDRESS

1. People prefer to use easy-to-remember names instead of IP addresses 
2. Domain names (a part of the URL) are alphanumeric names for IP addresses.                               e.g., neon.ece.utoronto.ca, www.google.com, ietf.org
3. The domain name system (DNS) is an Internet-wide distributed database that translates between domain names and  IP addresses.
4. IP address and domain name allocation requires central administration to avoid duplication   
5.  Previously administered by U.S. government contract (NSI)

OVERVIEW OF THE INTERNET

ARPANET

• Network become internet.
• First published: 1967(under the directions of the U.S. Advanced Research Projects Agency (ARPA)
• 1969 : ARPANET  took advantage of the new idea which is sending information in small unit called packets that could be routed on different paths and reconstructed at  their destination. 
• 1970 : Expand the size of the network which had become a network of networks, in an orderly way.
• 1980 : ARPANET handed over to separate new military network, the Defense Data Network, and NSFNet, network of scientific and academic computers funded by the National Science Foundation.
• 1995 : NSFNet turn began a phased withdrawal to turn the backbone of the internet over to a consortium of commercial backbone providers.
• 1971 : ARPA's name changed to Defense Advance Research Projects Agency(DARPA)

INTERNET

A means of connecting a computer to any other computer anywhere in the world via dedicated routers and servers. When two computers are connected over the internet, they can send and receive all kinds of information such as text, graphics, voice, video, and computer programs.No one own Internet , although several organizations the world over collaborate inits functioning and development. The high-speed, fiber-optic cables (backbones) through which the bulk of the Internet data travels are owned by telephone companies in each country. Later universities and other US institutions connected to it. this result in ARPANET growing beyond everyone's expectations and acquiring the name 'internet'.

Resource : http://www.businessdictionary.com/definition/internet.html

INTRANET

An intranet is a private network that is contained within an enterprise. It may consist of many interlinked local area networks and also use leased lines in the wide area network. Typically, an intranet includes connections through one or more gateway computers to the outside Internet. The main purpose of an intranet is to share company information and computing resources among employees. An intranet can also be used to facilitate working in groups and for teleconferences.

Resource : http://searchwindevelopment.techtarget.com/definition/intranet

EXTRANET

An extranet is a controlled private network allowing customers, partners, vendors, suppliers and other businesses to gain information, typically about a specific company or educational institution, and do so without granting access to the organization's entire network. An extranet is often a private part of a website. It is restricted to select users through user IDs, passwords and other authentication mechanisms on a login page.

ADVANTAGES 

INTERNET	INTRANET	EXTRANET
Gain information, knowledge and learning. Example :            Search engine like google, can ask virtually any question and find a web page with an answer.            Millions of videos on site like youtube that help to explain various topics .           Online course can be taken to help teach you about many different subjects.	Communication within an organization or business company , landscape or potrait.          Helpful to converse planned intiative that has transportation are chat, email,  and blogs.            Actual world example of intranet is nestle had a number of food processing plants.	Reduced margin of error.         Reduce your margin of error, especially when you use it to give specific groups access to internal applications.          Involve something as simple as giving customers access to their order histories, or something as complex as processing orders from distributors and suppliers.
Connectivity, communication, and sharing Example :           Send an e-mail to anyone in the world.         Its delivered in less than a minute.	Offering business operations and administration solutions because it also being used as a platform of mounting and organizing applications across the internet world.	Flexibility.           Everyone can operate when and where it’s most convenient.           This self-serve approach frees you from unnecessary meetings and phone tag, and it cuts down on the costs associated with in-person information exchanges. For example, an extranet may allow you to provide customer-service information outside of regular business hours.
Banking, bills and shopping Example :            Everyone easy access to compare prices between companies.            See what others thinks about a product through online reviews to help make better purchasing decisions.	Time saving           There is no need to maintain physical documents such as procedure manual, requisition forms, and internet phone list.	Timely and accurate information.            On an extranet you can instantly change, edit, and update sensitive information such as price lists or inventory information.
Selling and making money	Offer improve teamwork through which teamwork is enabled and all certified users can get access to information.	Reduced inventory.            By linking your inventory system directly to a supplier, you can process orders as soon as the system knows you need them, thus reducing the stock you keep on hand and making the procurement process more efficient.
Donations and funding Example : People can quickly make a donation to their favourite charity Help fund projects and idea at their blog	Intranet providing cross platform capability for UNIX, Mac, Windows.	Build customer loyalty.            Extranets make business easier for your customers. The more you make timely, accurate information available to your customers, the more likely it is you’ll keep their business.

DISADVANTAGES

Disadvantages of Internet

• Theft of personal information such as name, address, credit card number etc.
• Virus threats nothing but a program which disrupts the normal functioning of your system.
• Spamming refers to receiving unwanted e-mails in bulk, which provide no purpose and needlessly obstruct the entire system.
• Pornography this is perhaps the biggest threat related to children’s healthy mental life. A very serious issue concerning the Internet.Though, internet can also create havoc, destruction and its misuse can be very fatal,

Disadvantages of Intranet

•Collaborative applications for Intranet are not as powerful as those offered by traditional groupware 

 For instance, Intranet includes no built-in data replication or directory services for remote users, while groupware packages such as Lotus Notes do.

•Short-term risk -

There are limited tools for linking an Intranet server to database or other  back-end mainframe-based applications. Programming standards for the Web, such as common gateway interface (CGI) and Java are fairly new and just maturing.

•Less back-end integration -

With Intranets, firms have to set up and maintain separate applications such as E-mail and Web servers, instead of using one unified system as with group ware.

 Disadvantages of Extranet

• Extranets can be expensive to implement and maintain within an organization (e.g.: hardware, software, employee training costs) — if hosted internally instead of via an ASP.
• Security of extranets can be a big concern when dealing with valuable information. System access needs to be carefully controlled to avoid sensitive information falling into the wrong hands. 
• Extranets can reduce personal contact (face-to-face meetings) with customers and business partners. This could cause a lack of connections made between people and a company, which hurts the business when it comes to loyalty of its business partners and customers.
• People who are illiterate & don’t have any technology knowledge can feel some problem that how to use it.
• Face to face contact is impossible .so we can not meet personally to any customer or dealer.
• As eye to contract is impossible so we cannot judge that who is using our information is true or wrong. It is possible that he or they can misuse our secrets or our information.
• Small business or small corporate cannot bear this technology’s cost as it can increase their expenses.
• Our business competitors or our business enemies can misuse our secrets information.
• It reduces the number of employment.
• There are many places, where the technology is not developed so it could not work there.

NETWORK TOPOLOGY(DIFFERENCE BETWEEN LAN, MAN, AND WAN)

LAN(LOCAL AREA NETWORK)

A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link to a server. Typically, a LAN encompasses computers and peripherals connected to a server within a distinct geographic area such as an office or a commercial establishment. Computers and other mobile devices use a LAN connection to share resources such as a printer or network storage.

MAN(METROPOLITAN AREA NETWORK)

A metropolitan area network (MAN) is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.

Examples of metropolitan area networks of various sizes can be found in the metropolitan areas of London, England; Lodz, Poland; and Geneva, Switzerland. Large universities also sometimes use the term to describe their networks. A recent trend is the installation of wireless MANs.

WAN(WIDE AREA NETWORK)

A wide area network (WAN) is a geographically distributed private telecommunications network that interconnects multiple local area networks (LANs). In an enterprise, a WAN may consist of connections to a company's headquarters, branch offices, colocation facilities, cloud services and other facilities. Typically, a router or other multifunction device is used to connect a LAN to a WAN. Enterprise WANs allow users to share access to applications, services and other centrally located resources. This eliminates the need to install the same application server, firewall or other resource in multiple locations.

WHAT THE DIFFERENCE BETWEEN LAN, MAN, AND WAN

Parameters	LAN	MAN	WAN
Full Form	Local Area Network	Metropolitan Area Network	Wide Area Network
What is it?	• Systems are close to each other in LAN  • contained in one office or building • one organization can have several LANs	• Large network which connects different organizations	• Two or more LANs connected  • Located over large geographical area
Distance coverage	Limited coverage, about upto 2 miles(or 2500 meters)	Limited coverage, about upto 100 miles(or 200 km)	Unlimited (usually in 1000Km) range, uses repeater and other connectivity for range extension
Speed of  operation	High, typically 10, 100 and 1000 Mbps	High, typically 100 Mbps	Slow, about 1.5 Mbps (May vary based on wireless technologies used)
Technologies used for medium	Locally installed, twisted pair, fiber optic cable, wireless (e.g. WLAN, Zigbee)	Locally installed and based on common carrier e.g. twisted pair, fiber optic cable etc.	Locally installed and based on common carrier e.g. twisted pair wires, fiber, coaxial cable, wireless including wireless and cellular network based
Applications	Used mainly by fixed desktop computers and portable computers (e.g. laptops) . Now-a-days it is used by smart phones due to emergence of WLAN network	Used mainly by desktop and mini computers.	Can be used by any devices, but desktop devices are mainly using this network type.

NETWORK TOPOLOGY(DIFFERENCE BETWEEN BUS, RING, AND STAR TOPOLOGY)

BUS TOPOLOGY

Bus topology is a specific kind of network topology in which all of the various devices in the network are connected to a single cable or line. In general, the term refers to how various devices are set up in a network.

Reference: https://www.techopedia.com/definition/17045/bus-topology

STAR TOPOLOGY

Alternatively referred to as a star network, star topology is one of the most common network setups. In this configuration, every node connects to a central network device, like a hub, switch, or computer. The central network device acts as a server and the peripheral devices act as clients.The picture to the right shows how this network setup gets its name, as it is shaped like a star.

Reference: https://teamultimate.in/wp-content/uploads/2017/02/star.png

RING TOPOLOGY

A ring topology is a network configuration in which device connections create a circular data path. Each networked device is connected to two others, like points on a circle. Together, devices in a ring topology are referred to as a ring network.

Reference: https://www.computerhope.com/jargon/r/ringtopo.htm

WHAT THE DIFFERENCE BETWEEN THIS THREE TOPOLOGY?

A Bus topology is a network topology in which all nodes connect to the network via a central cable, , called the bus. The bus acts as the shared communication medium that the devices are attached to. Any device that wants to communicate with other device on the network will send its data over the bus which will be send to all attached devices but the intended recipient will only process that packet. Thus bus topology is good and easy to setup for only a small number of devices, as devices and network utilization increases the performance issues and problems arise. If the bus is damaged then the whole network fails making bus topology a less preferred option.

In a Ring topology every device/node is connected to exactly two other nodes one on either side of it in closed loop fashion. All messages travel though the ring either in a clockwise direction or anti-clockwise direction. Ring topology is very rarely used today because they are expensive, difficult to install and manage. A failure in any single connection disrupts the ring topology thus also making ring topology a rare choice for network topologies.

Star topology is the most common topology and is the widely implemented. In a Star Topology every device is connected to a central device such as a switch. Star topology requires more cable as compared to other topologies but it mode robust as a failure in one cable will only disconnect the specific connected computer via that cable to the central device. The messages between systems will always flow via the central device and so if the central device fails the entire network will fail. Star topology is very easy install, manage and troubleshoot making it the most common topology in home and office networks.