Revision notes of Basics of Internet, Information & Computer Technology, Class 9 | Information & Computer Technology (Class 9) - Notes & Video PDF Download

Internet
• Internet: It is a global network of computer networks. It comprises of millions of computing devices that carry and transfer volumes of information from one device to the other.

 WWW
• History of World Wide Web (WWW):

→ Invented by Tim Berners-Lee in 1989.

→ By the end of 1990, the first Web page was served. 

→ In April 1993, the World Wide Web technology was available for anyone to use on a royalty-free basis.

• Definition of WWW: The World Wide Web (WWW) is an internet based service, which uses common set of rules known as Protocols, to distribute documents across the Internet in a standard way.

Difference between Internet and WWW
• The Internet is a massive network of networks. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols.

• The World Wide Web or simply Web, is a massive collection of digital pages to access information over the Internet. The Web uses the HTTP protocol, to transmit data and allows applications to communicate in order to exchange business logic. The Web also uses browsers, such as Internet Explorer, Google Chrome etc. to access Web pages that are linked to each other via hyperlinks.

Search Engines
• Definition: Search engines are the programs which are needed to extract the information from the internet.

• Working of Search Engines:

→ Web crawling: Web search engines work by storing information about many web pages. These pages are retrieved by the program known as Web crawler - which follows every link on the site. Web crawler may also be called a Web spider.

→ Indexing: Indexing also known as web indexing, it stores data to facilitate fast and accurate information retrieval. It is done by program called Indexer.

→ Searching: A web search query fetches the result from the web search engine entered by the user to meet his information needs.

• Examples: Google, Yahoo, Bing, Ask

Web Server
• Definition: A server is a computer that provides data to other computers. The entire structure of the Internet is based upon a client-server model.

• Uses:
→ The most common use of web servers is to host websites.
→ The web server also deliver web pages to clients.

• The communication between the client node and server node takes place using the Hypertext Transfer Protocol (HTTP).

Server Software
• A web server commonly known as HTTP server or application server is a program that serves content using the HTTP protocol.
• The server content served by the web server can be static content or dynamic content.
• Different Server Software:

→ Apache web server - the HTTP web server: This is free and open source web server and can be installed and made to work on almost all operating systems including Linux, Unix, Windows, FreeBSD, Mac OS X and more. Almost, 60% of the web server machines run the Apache web server.

→ Apache Tomcat: This is free and open source web server that can run on different operating systems like Linux, Unix, Windows, Mac OS X, Free BSD. It was developed to support servlets and JSP scripts. It can serve as a standalone server.

→ Lighttpd: It is a free and open source web server distributed with the FreeBSD operating system. This is fast, secure and consumes much less CPU power. Lighttpd can also run on Windows,
Mac OS X, Linux and Solaris operating systems.

→ Jigsaw: Jigsaw (W3C’s Server) is introduced by the World Wide Web Consortium. It is open source and free and can run on various platforms like Linux, Unix, Windows, Mac OS X Free BSD etc. Jigsaw is written in Java thus can run CGI scripts and PHP programs.

Services Provided by the Servers
• Many of the servers are based on Cloud computing which is popular amongst the researchers, scientists & entrepreneurs.
• Cloud Computing is distributed computing over a network, and has the ability to run a program or application on many connected computers at the same time.
• Various services provided by the Web server are:

→ Cost Efficient: Web server is the most cost efficient method to use, maintain and upgrade. ALso, one-time-payment, pay-as-you-go and other scalable options available, which makes it very reasonable for the company.

→ Resource Sharing: Web Server has the capability to store unlimited information such as Google Drives, Cloud computing etc. The space where the data can be stored is shared by the other users at the same time like hard disk can be shared on physical network as LAN.

→ Data Sharing: With the help of web servers one can easily access the information from anywhere, where there is an Internet connection using Google docs such as Documents, Excel sheets, Drawings, Powerpoint presentations etc.

→ Backup and Recovery: The entire process of backup and recovery much simpler than other traditional methods of data storage.

Types of Server
• Mail Server: Mail Servers provides a centrally-located pool of disk space for network users to store and share various documents in the form of emails.
• Application Server: An application server acts as a set of components accessible to the software developer through an API defined by the platform itself.
• File Transfer Protocol (FTP) Server: FTP uses separate control and data connections between the client and the server. FTP users may authenticate themselves in the form of a username and password, but can connect anonymously if the server is configured to allow it.
• Database Server: A database server is a computer program that provides database services to other computer programs or computers using client-server model.
• Domain Name System (DNS) Server: A name server is a computer server that hosts a network service for providing responses to queries.

→ Function fo DNS Server:
♣ Primary function is to translate human- memorable domain names and hostnames into the corresponding numeric Internet Protocol (IP) addresses.
♣ The secondary function of DNS is to recognize a name space of the Internet, used to identify and locate computer systems and resources on the Internet.

Web Site
• Definition: The collection of web pages on the World Wide Web that is accessed by its own Internet address is called a Web site.

• Difference between Website and Portal

→ Web portal is a medium by which users access the resources, while a website is a destination in itself.

→ Portals and websites are distinct entities which are linked together, but they should not replace each other.

→ A website is also a portal, if it broadcast information from different independent resources where as Web Portal refers to a website or services that provide varied resources and services such as email, forums, search engines and online shopping malls.

Components of Website
• Contents of a Web Page: A webpage of a website must contain the basic elements such as Page title, URL, file name, header, footer, navigation, web page content are all parts to the composition of a web page.

• Website Graphics: Always use web graphics which have been optimized for optimum download speed, as the web hosting space affects the performance of the website.

• Heading of the site: Headings in a website play a crucial role as they not only present a clear structure of the web page to the audience and help the search engines to retrieve the required information.

• Effective Colour Contrast: It is very important to use that colour scheme that must not have any difficulty in reading a web page. 

 Elements of Website
• Good Visual Design: A site must be appealing and if required, must be professional. Your site reflects your company, your products and your services.

• Screen Resolution: We need to make sure website looks good in all screen resolutions.

• Colour Scheme & Text Formatting: To make the website presentable appropriate colour scheme must be used. We need to use 2 or 3 primary colours that reflect the purpose of site. Add contrast colours in your site, which helps the user to easily read the text. Use fonts that are easy to read and available and maintain appropriate font size.

• Insert Meaningful Graphics: Graphics are important, as they provide the site a legible and interactive appearance. We must ensure that images fit in website and they load quickly. Also, don' use too many images with less text.

• Simplicity: Keep your site simple and allow for adequate white space. Don’t overload your site with complex design, animation, or other effects to impress your viewers.

• Relevant Content: Include relevant information along with style, to help the visitors to make a decision.

• Navigation: Keep your site simple and well organized. Don't use fancy menus and place all the menu items at the top of your site. Include Site Maps in your site to reduce the number of top level navigation items. Every component of your site should work quickly and correctly.

• Minimal Scroll: Use less scrolling as  users do not like scrolling the page instead they need to see all the information on one screen.

• Consistent Layout: Always use a consistent layout in the whole website which will help you to retain the theme of the site.

• Cross-platform/browser Compatibility: Create a website which should be platform independent as many web browsers are being used by the users.

Construction of Website
• Step 1- Hosting: The first step in constructing a website is to decide about the web hosting provider for your site. Choose between free and paid hosts.

• Step 2 - Domain Name: You can plan your website using a domain name and without using a domain name. A domain name provides extra branding for your site and makes it easier for people to remember the URL.

• Step 3 - Plan Your Website: After deciding the domain and your URL, you can start planning your site. You need to decide the audience aimed at. 

• Step 4 - Build Your Website Page by Page: For building a website you need to work on one page at a time.

• Step 5 - Publish Your Website: After the completion of the design now it is the time to publish your website on web. 

• Step 6 - Promote Your Website: There are many ways to promote a website such as web search engine, word of mouth, email, and advertising.

• Step 7 - Maintain Your Website: It is the last step of constructing a site which helps in keeping your site updated with the latest trends of market.

Software used to Create Website:

• CoffeeCup Free HTML Editor

• Notepad++

• PageBreeze

• Firebug

• Bluefish Editor

• Brackets

• KompoZer

• OpenBEXI

• GIMP

• BlueGriffon

 WebPage
• Definition: A Web page also known as Electronic Page, is a part of the World Wide Web. It is the basic unit of every Web site. It is a combination of text and graphics.

• Static Web Page: Also called flat page or stationary page. It is a web page that is delivered to the user exactly as stored. A static web page displays the same information for all users, such versions are available and the server is configured to do so.

• Dynamic Web Page: It is a web page which needs to be refreshed every time whenever it

opens in any of the web browsers to display the updated content of the site.

• How Web Page works: 

→ The server receives the request for a page sent by your browser.
→ The browser connects to the server through an IP Address; the IP address is obtained by translating the domain name.
→ In return, the server sends back the requested page.

• Difference between Webpage and Website:
A web page is one single page of information, while a website is made up of a number of different web pages connected by links known as Hyperlinks.

 Web Browser
• A browser is a software that lets you view web pages, graphics and the online content.
• What browsers do: Browser software convert HTML and XML into readable documents.
• Examples: Google Chrome, Firefox, Internet Explorer, Safari, Opera and UC Browser.
• Tool Bar: The Tool Bar is much like the Menu Bar stretching from left to right across the top of the screen.
 

→ Back button : Helps to open the previously opened website.

→ Back history : Helps to bring up a list of the sites visited.

→ Forward button : This button will only be available once you have used the Back button at least once. It helps to take you to the page you just left when you clicked on the Back button.

→ Forward history : That brings up a list of the sites you have visited and then used the Back button to return.

→ Stop : Helps to stop the current download.

→ Refresh : Gives the most recent version of the page that we are on.

→ Home : Helps you to instantly get back home page (first page).

→ Search : Helps to retrieve the specified files using web search engine.
 → Favourites : Helps to open up the most frequently visited sites.
→ History : Helps you to see where you have been on the Internet.

• SSL: The Secure Sockets Layer (SSL) is a protocol, uses Hypertext Transfer Protocol (HTTP) and Transport Control Protocol (TCP) for managing the security of a message transmission on the Internet.

→ The “sockets” term refers to the sockets method of passing data back and forth between a client and a server program in a network or between program layers in the same computer.

→ SSL uses the public-and-private key encryption system, which also includes the use of a digital certificate.

 Blogs
• Definition: A blog is a website like any other, but it is intended to offer personal opinions of people on their hobbies, interests, commentaries, photo blogs, etc.
• Two ways of starting a blog:

→ Free blog hosting: You do not need a server to start your own blog. There are plenty of free, open source blogging software you can install. For example WordPress and Moveable Type.

→ Paid blogging: Purchase space from company for hosting website and the blogger has to pay for the same till the time he is using the available space.

• Category of blogs:

→ Personal blogs

→ News and views

→ Company blogs

→ Micro blogs

• Personal blog: It a way of giving words to your thoughts. A typical blogger may be keen on posting stories about his interests.

• News and views: There are number of news and television companies having professionaljournalists who post stories and views about the latest events. Visitors can comment their opinions as well. BBC is a popular example of the same.

• Company blogs: Many companies run blogs to let their customers and clients know about the new products coming up or progress being made on some project.

• Micro-blogs: This is a new type of blog where you post very short comments that others can follow and a powerful way for professionals to keep in touch with each other. Twitter is the best example.

 Bloggers
• A person who writes a blog is simply known as a blogger.
• Features of good blogger:
→ Write unique but meaningful content. Try keeping the language simple and concise and incorporate some surprise elements. Find a topic that would intrigue your readers or an issue that people are looking out for more information.

→ Don’t make it boring. Avoid clichés. Keep your writing informal, if possible funny or quirky and create a perfect balance between keeping the mood light and professional enough to suggest you are serious about your matter.

→ You need to express knowledge in a right way and communicate properly to your readers. Write crisp, short, active sentences with powerful verbs. Ensure that your content is error-free, proofread and edit your work meticulously and only when you are satisfied with it, hit the publish button.

→ The title tempt readers to open the link and leave satisfied but still wanting to know more

about other blogs.

• Advantages of blogging:
→ We can work on blog anytime and anywhere in the world, all you need is your laptop or a desktop computer and wireless internet services.
→ You are your own employee. When blogging, you can blog any time you want to whenever you think of something that is relevant to your blog.
→ As a blogger, you are flexible and can choose to write about anything in the world as long as it benefits you and befits your opinions and thought process.
→ Very quick and easy to set up, do not need much technical knowledge.
→ Easy and quick to update or add new posts. People can leave comments on your blog and you can comment on other persons’ blogs, too.

• Disadvantages of blogging:
→ You need to be patient because you don’t start earning in a single day. Readership takes time to develop within people.
→ Blogging is time-consuming. You need to be disciplined. Finding time to write regular updates can become a chore.
→ You need to be very active as a blogger so that people can read your blog posts.
→ As you know the public to everyone, you need to put a check on your language.
→ There are many very dull blogs around. You may have to look at many before you find some worth reading.

 URL
• Definition: URL’s, or ‘uniform resource locators’, are the web browser addresses of internet pages and files.
• Format of a url: Protocol://site address/path/filename

• Parts of URL:

→ Protocol which ends with a ‘//:’

→ Host computer which ends with web extensions such as .com,.org etc.

→ Filename or page name which displays the related information.

• An Absolute URL is independent or free from any relationship. It specifies the exact location of a file or directory on the internet. Each absolute URL is unique, which means that if two URLs are identical, they point to the same file.

In above URL specifies an image file hardware.gif located in the images directory, under

domain name www.developers.com.

• A Relative URL is targeted to a file or directory in relation to the present file or directory. The relative URLs are shorter than absolute URLs and hence the file size of the web page would reduce, if you use the former.

→ For example:

If we want to include the image file hardware.gif stored in the images directory of www.developers.com domain on this page using an absolute URL. The <img> tag for this image display will be as follows: using a relative url in an <IMG> tag.

<img alt="" src="https://edurev.gumlet.io/uot;https://edurev.gumlet.io/dquo;../images/hardware.gif” width=”...” height=”...” />

 Protocols
• Definition: A protocol is a set of rules that governs the communication between computers on a network.
• The most popular protocols used on internet are the World Wide Web, FTP, Telnet, Gopherspace, instant messaging, and email.

• Types of Protocols:
→ TCP/IP: TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic point-to-point meaning each communication is from one point (or host computer) in the network to another point or host computer communication protocol on the Internet.

♠ It is used as a communication protocol in all types of networks.

♠ TCP/IP is a two-layer protocol. 

• HTTP stands for HyperText Transfer Protocol, is a set of standards that allows users of the World Wide Web to exchange information found on web pages on internet.

♠ It defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands.

♠ The HTTP provides a standard for Web browsers and servers to communicate.

• File Transfer Protocol (FTP) is a standard protocol used on network to transfer the files from one host computer to another host computer using a TCP based network, such as the Internet.

♠ FTP uses separate control and data connections between the client and the server.

♠ To use FTP server, users need to authenticate themselves using a sign-in protocol, using a username and password, but can connect anonymously if the server is configured to allow it.