CBSE Class 10 Computer Science Basics Of Information Technology Notes

INTERNET 

Today, almost every person is directly or indirectly affected by the Internet. The Internet is an interconnection between several computers of different types belonging to various networks all over the world.

• History of Internet

In 1969, the Department of Defence (DoD) of the United States of America developed a network called Advanced Research Projects Agency Network (ARPANET). Later, the military allowed universities to join the network for sharing the hardware and software resources. The network grew bigger and bigger and gave birth to the present-day Internet. 

Internet Related Terminology 

•  World Wide Web

The Internet is an inter-connection of computer networks, whereas WWW is a collection of digital pages to access information over the Internet. WWW is an information system of interlinked hypertext documents that are accessed via the Internet. 

•  Webpage

The WWW comprises a large collection of documents called WebPages. A webpage is what you see in your browser when you are on the internet. Think of the webpage as a page in a magazine. You may see text, photos, images, diagrams, links, advertisements and more on any page you view. 

Several WebPages on a related subject make a website. 

•  Website: A website is a collection of one or more related WebPages, images, videos hosted on a web server. 

•  Homepage: It is the first page of a website. 

•  Web Browsers: Browsers display webpages. The most popular web browsers include

(a)  Chrome by Google,

(b)  Firefox by Mozilla,

(c)  Internet Explorer by Microsoft, 

(d) Safari by Apple, ü  but there are many others. 

• Blog: A blog is a modern online writer's column. 

•  Newsgroup:  A newsgroup is an online discussion forum. Similar to e-mails except that instead of sending your message to someone‟s mailbox, the message is posted on a bulletin board where anyone can read it and respond to it. This allows a discussion to take place among several people. 

•  HTML: Hypertext Markup Language (HTML) is the standard markup language for creating web pages and web applications. 

•  Web Address: it is an internet address of a website, file, or document in the general format. http://www.address/directories/filename. Every computer connected to the internet has its unique web address, without which it cannot be reached by other computers 

•  E-mail Address

The  general  format  of  an  email  address  is local-part@domain,  and  a  specific  example is jsmith@example.com. An address consists of two parts. The part before the  @symbol (local-part) identifies the name of a mailbox. This is often the username of the recipient, e.g., jsmith. The part after the @ symbol (domain) is a domain name that represents the administrative realm for the mail box, e.g., a company's domain name, example.com. 

•  URL

Uniform Resource Locators—URLs— are the web browser addresses of internet pages and files. With a URL,  you can locate and bookmark specific pages and files for your web browser. URLs can be found all around us. They may be listed at the bottom of business cards, on TV screens during commercial breaks, linked in documents you read on the internet or delivered by one of the internet search engines. 

The format of a URL resembles this: 

    http://www.examplewebsite.com/mypage

 This is frequently shortened to this: 

   www.examplewebsite.com/mypage

 Sometimes they are longer and more complicated, but they all follow acknowledged rules for naming URLs. 

URLs consist of three parts to address a page or file: 

•   The protocol  (set  of rules  for communications) is  the portion  ending in  //:  Most WebPages use the protocol http or https, but there are other protocols. 

•   The host or top-level domain, which frequently ends in .com, .net, .edu or .org but can also end in one of many others that have been officially recognized. 

•   The filename or page name itself. 

•   HTTP

Http is the acronym for "Hypertext Transfer Protocol," the data communication standard of web pages. When a web page has this prefix, the links, text, and pictures should work properly in your web browser. 

Https is  the  acronym  for  "Hypertext  Transfer  Protocol  Secure."  This  indicates  that  the webpage has a special layer of encryption added to hide your personal information and passwords from others. Whenever you log in to your online bank account or a shopping site that you enter credit card information into, look for "https" in the URL for security. 

FTP: The File Transfer Protocol (FTP) is the standard network protocol used for the transfer of computer files between a client and server on a computer network. 

•  Downloading and Uploading Files from a Remote Site:

Downloading is a broad term that describes transferring something you find on the internet or World Wide Web to your computer or other device. Commonly, downloading is associated with songs, music and software files. For example, you might want to:

.  Download a new musical ringtone for your cell phone 

.   Download a trial copy of Microsoft Office. 

The larger the file you are copying, the longer the download takes to transfer to your computer. 

Uploading is the process of moving digital files such as photographs or documents from your computer and placing them on to a central server so that someone else can retrieve them or to a website so others can see them. For example, you might save photographs from your digital camera on to your computer and upload them on to a social network such as facebook, where you can allow friends and family to see them. 

SERVICES AVAILABLE ON INTERNET 

•  Information Retrieval

Internet  is  an  ocean  of  information  on  nearly  every  field,  including  education,  sports, business, and career. 

Information retrieval, thus, covers accessing and obtaining information from the Internet. Exploring information on the Internet is called surfing the Internet.

• Locating Site using Search Engines

One of the most important software used for information retrieval in the Internet is the search engine. A Search Engine is a program that is designed to search for information on the Internet. It searches all files over Internet with the specified keywords and returns a list of the documents containing them. 

Search Engine broadly consists of three components: Crawler, Index and Search algorithm. Information can be in the form of WebPages, images, and other types of files.

A few examples of search engines are Google, Yahoo, Khoj, Infoseek, etc. Khoj.com is Indian Local Search Engine.  

• Finding People on the Net

Many resources are available on the Internet for finding peoples. You can find your friends, colleagues and classmates through their name, email address, etc.., on websites that support this kind of search. This is a quick way to connect to and find people. Some of the popular sites available are: facebook, twitter, isearch, whowhere, whitepages.