Chapter 1: Basics of Internet

Class: IX | Subject: Information and Computer Technology

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Key Concepts

1. The Internet, The Internet evolved in 1969 under the project ARPANET (Advanced Research Projects Agency Network) to connect computers at different universities and US defence., In the 1990s, the internetworking of ARPANET, NSFnet, and other private networks resulted in the Internet., The Internet is a "global network of computer networks", millions of computing devices carrying and transferring information. Desktop computers, mainframes, GPS units, cell phones, car alarms, and video game consoles are all connected.

2. World Wide Web (WWW), Invented by Tim Berners-Lee in 1989. The first web page was served by end of 1990. WWW technology was made royalty-free in April 1993., The WWW is an internet-based service that uses a common set of rules (protocols) to distribute documents across the Internet in a standard way., The Web is viewed through web browsers such as Google Chrome, Internet Explorer, Mozilla Firefox.

3. Internet vs WWW

Internet	WWW
Massive network of networks connecting millions of computers globally	Massive collection of digital pages accessed over the Internet
Uses a variety of protocols	Uses the HTTP protocol specifically
Infrastructure layer	Service/application layer on top of the Internet

4. Search Engines, Programs that extract information from the internet. They work with two programs:

• Spider (Web crawler): Fetches as many documents as possible, follows every link on a site.
• Indexer: Reads the documents and creates an index based on the words contained in each document., A search engine works in this order: Web crawling --> Indexing --> Searching., Examples: Google, Yahoo, Bing, etc.

5. Web Servers, A server is a computer that provides data to other computers. The Internet is based on a client-server model., A web server delivers web content (pages, images, style sheets, scripts) that can be accessed through the Internet using HTTP., Content can be static (pre-existing) or dynamic (generated on the fly).

Server Software Examples

Software	Description
Apache HTTP Server	Free, open source; runs on Linux, Unix, Windows, Mac OS X; ~60% of web servers use it
Apache Tomcat	Free, open source; supports servlets and JSP scripts
Lighttpd	Free, fast, secure, low CPU usage
Jigsaw (W3C)	Written in Java; runs CGI scripts and PHP programs

Services Provided by Web Servers

1. Cost Efficient, cheaper than traditional desktop software
2. Resource Sharing, unlimited storage (Google Drive, cloud computing)
3. Data Sharing, access information from anywhere with internet (Google Docs)
4. Backup and Recovery, easier than traditional methods

Types of Servers

1. Mail Server, stores and shares documents in the form of emails
2. Application Server, supports construction of dynamic pages
3. FTP Server, transfers files between client and server using FTP protocol
4. Database Server, provides database services using client-server model (e.g., MySQL)
5. DNS Server, translates human-readable domain names into numeric IP addresses

6. Websites, A website is a collection of related web pages on the WWW, accessed by its own Internet address. Each website has a home page and additional pages., A web portal is a medium by which users access resources from different independent sources (e.g., AOL, iGoogle, Yahoo), while a website is a destination in itself.

Components of a Website

1. Contents of a web page (title, URL, file name, header, footer, navigation, content)
2. Website graphics (optimized for download speed)
3. Heading of the site
4. Effective colour contrast

Elements of a Website, Good visual design, Screen resolution (1024 x 768 pixels was the average), Colour scheme and text formatting (2-3 primary colours, 10-12 pt font), Meaningful graphics, Simplicity, Relevant content, Navigation, Minimal scrolling, Consistent layout, Cross-platform/browser compatibility

Steps to Build a Website

1. Hosting, choose a web hosting provider (free or paid)
2. Domain Name, plan with or without a domain name
3. Plan Your Website, decide audience and site type
4. Build Page by Page
5. Publish, using hosting tools or FTP clients
6. Promote, SEO, word of mouth, email, advertising
7. Maintain, regular testing and content updates

Software Used to Create Websites

CoffeeCup Free HTML Editor, Notepad++, PageBreeze, Firebug, Bluefish Editor, Brackets, KompoZer, OpenBEXI, GIMP, BlueGriffon

7. Web Pages, A web page is the basic unit of a website, containing text, graphics, articles, photographs.

• Static web page: Delivered exactly as stored; displays the same information for all users.
• Dynamic web page: Refreshed every time it opens to display updated content.

How a Web Page Works

1. The browser sends a request to the server.
2. The browser connects to the server through an IP address (obtained by translating the domain name).
3. The server sends back the requested page.

8. Web Browsers, Software that lets you view web pages, graphics, and online content. Designed to convert HTML and XML into readable documents., Popular browsers: Google Chrome, Firefox, Internet Explorer, Safari, Opera, UC Browser

Toolbar Buttons

Button	Function
Back	Opens previously opened website
Forward	Takes you to the page you left when you clicked Back
Stop	Stops the current download
Refresh	Gives the most recent version of the current page
Home	Returns to the home page
Search	Retrieves specified files using a search engine
Favourites	Opens frequently visited sites
History	Shows where you have been on the Internet

9. SSL (Secure Sockets Layer), A protocol that uses HTTP and TCP for managing the security of message transmission on the Internet., Uses the public-and-private key encryption system, including digital certificates.

10. Blogs, A blog (short for "web log") is a website intended to offer personal opinions on hobbies, interests, commentaries, etc., Started as online personal diaries; now used by businesses too.

Types of Blogs

1. Personal blogs, most popular; about personal interests
2. News and views, professional journalists posting stories and views (e.g., BBC)
3. Company blogs, companies informing customers about new products
4. Micro-blogs, very short comments for professionals to stay in touch (e.g., Twitter)

Starting a Blog

1. Free blog hosting, WordPress, Moveable Type
2. Paid blogging, company provides space for a fee

Advantages of Blogging, Work anytime, anywhere, Flexibility in topic choice, Quick and easy to set up, Easy to update; allows comments

Disadvantages of Blogging, Readership takes time to develop, Time-consuming and requires discipline, Must be very active to retain followers, Content is public, must watch language, Many dull blogs exist

11. URL (Uniform Resource Locator), The web browser address of internet pages and files. Every file on the Internet has a unique URL.

• Format: Protocol://site address/path/filename

Parts of a URL

Example: http://www.banks.com/login/password.htm

1. Protocol: http
2. Host computer name: www
3. Domain name: banks
4. Domain type: com
5. Path: /login
6. File name: password.htm

Absolute vs Relative URLs

• Absolute URL: Specifies the exact location of a file (e.g., http://www.developers.com/images/hardware.gif). Each absolute URL is unique. Preferred for site maintenance.
• Relative URL: Targeted to a file in relation to the present file/directory (e.g., ../images/hardware.gif). Shorter, reduces file size of web pages.

12. Protocols, A protocol is a set of rules that governs communication between computers on a network., The Internet has many layers of information; each layer is dedicated to a different kind of documentation, called protocols.

Types of Protocols

Protocol	Full Form	Purpose
TCP/IP	Transmission Control Protocol / Internet Protocol	Basic point-to-point communication on the Internet. TCP manages assembling/reassembling of packets; IP handles addressing.
HTTP	HyperText Transfer Protocol	Allows exchange of information on web pages; defines how messages are formatted and transmitted.
FTP	File Transfer Protocol	Transfers files from one host to another. Uses separate control and data connections. Supports username/password authentication.

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Important Definitions

Term	Definition
Internet	A global network of computer networks connecting millions of computing devices
WWW	An internet-based service using protocols to distribute documents across the Internet
ARPANET	Advanced Research Projects Agency Network, precursor to the Internet (1969)
Search Engine	A program that extracts information from the internet using web crawling, indexing, and searching
Web Server	A computer that provides data to other computers using HTTP
Cloud Computing	Distributed computing over a network; ability to run programs on many connected computers simultaneously
Website	A collection of related web pages on the WWW accessed by its own Internet address
Web Portal	A medium providing access to resources from different independent sources
Web Page	A single document on the Web, containing text, graphics, and other media
Web Browser	Software designed to convert HTML/XML into readable documents for viewing web content
SSL	Secure Sockets Layer, protocol for managing security of message transmission using public/private key encryption
Blog	A website (short for "web log") offering personal opinions, commentaries, or business information
URL	Uniform Resource Locator, the unique address of a file on the Internet
Protocol	A set of rules governing communication between computers on a network
DNS	Domain Name System, translates domain names into numeric IP addresses
Static Web Page	A page delivered exactly as stored, displaying the same information for all users
Dynamic Web Page	A page that refreshes every time it opens to display updated content

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Key Points

1. The Internet originated from ARPANET in 1969.
2. The WWW was invented by Tim Berners-Lee in 1989 and is a part of (not the same as) the Internet.
3. Search engines use spiders/crawlers and indexers to find and organize information.
4. Web servers deliver content using HTTP; Apache is the most widely used server software.
5. A website is a collection of web pages; a web portal aggregates content from multiple sources.
6. Static pages show the same content to all users; dynamic pages update with each visit.
7. SSL provides security using public-private key encryption and digital certificates.
8. URLs have three essential parts: protocol, host computer, and filename.
9. Absolute URLs specify the complete path; relative URLs are shorter and context-dependent.
10. TCP/IP, HTTP, and FTP are the three most important Internet protocols.

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Practice Questions

1. Define: URL, FTP, Blogger, ARPANET, Protocol, Blog, TCP/IP, HTTP.
2. Define WWW. How is it different from the Internet?
3. Briefly explain the various types of servers.
4. Differentiate between a static webpage and a dynamic webpage.
5. What is a Search Engine? How does it work?
6. What is a Web Server? What are the various services provided by web servers?
7. What is a Web Page? How does it work and how is it different from a website?
8. What is meant by Cloud Computing?
9. What is a Web Site? How does it differ from a Web Portal?
10. What are the various steps involved while creating a Web Site?
11. Name some software used to create a Website.
12. What do you mean by a Web Browser?
13. What is meant by SSL?
14. Discuss the various types of blogs.
15. Briefly explain the elements of a website.

Lab Activities, List URLs of commercial and non-commercial websites; find domain names, servers, and protocols., Name all e-commerce websites., Create an e-group on a social networking site., List all personal blogging sites., List all popular search engines., Find IP addresses of favourite sites using a search engine., Make a collage of web browser logos and compare features.