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Lesson 2Using the Internet:
ObjectiveThis page describes the Structure of the Internet.

Engaging and using the Internet

Think of the Internet as a giant computer network linking computers from all over the world. Then add millions of users and for some users, the Internet is an infrastructure to access public and private networks, social networks, etc. For other users, it is the essential bridge for the Web and email. Which group do you belong to? Either is correct, as long as users best define the Internet as comprising four essential parts: computers, networks, software, and users.
Essential parts of the Internet
Essential Parts of the Internet

The Internet supports a wide range of services that are available to users. Here are the basic Internet services:
  1. Electronic mail (email)
  2. World Wide Web (the Web)
  3. Mailings lists and newsgroups
  4. Chat
  5. File Transfer Protocol (FTP)
  6. Search Engines

World Wide Web

One has millions of Web sites form the enormous resource database called the World Wide Web (the Web). To get onto the Web and find Web sites you will need a browser. Firefox and Microsoft Internet Explorer are the two most popular browsers. You can learn about each at their respective Web sites. To see how the Internet has evolved, review the history of the Internet.

History of the Internet
The United States Defense Department created the Internet in the 1960's under the name ARPAnet (Advanced Research Projects Agency Network) as an experimental network. The ARPAnet connected computers across the United States, regardless of operating system or hardware, to ARPA research sites. But costs were high. In the meantime, the National Science Foundation built its own high-speed network, the National Science Foundation Network (NSFNET), that connected supercomputer sites to it. The NSFNET made the ARPAnet obsolete. In 1994, Tim Berners-Lee and Robert Cailliau at CERN, a physics research center in Switzerland, developed the Web. Note that the Web is not the Internet; the Web runs on the Internet. In 1995, the National Science Foundation closed the NSFNET, passing all the Internet traffic to corporate networks such as MCI. This marked the beginning of the Internet.
Time line for the history of the internet
Time line for the history of the internet

Page Rank

PageRank is a link analysis algorithm that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set. The algorithm may be applied to any collection of entities with reciprocal quotations and references. The numerical weight that it assigns to any given element E is also called the PageRank of E and denoted by PR(E).

Information Retrieval

In addition to a range of media, information retrieval involves a range of tasks and applications. The usual search scenario involves someone typing in a query to a search engine and receiving answers in the form of a list of documents in ranked order. Although searching the World Wide Web (web search) is by far the most common application involving information retrieval, search is also a crucial part of applications in corporations, government, and many other domains. Vertical search is a specialized form of web search where the domain of the search is restricted to a particular topic. Enterprise search involves finding the required information in the huge variety of computer files scattered across a corporate intranet. Web pages are certainly a part of that distributed information store, but most information will be found in sources such as email, reports, presentations, spreadsheets, and structured data in corporate databases. Desktop search is the personal version of enterprise search, where the information sources are the files stored on an individual computer, including email messages and web pages that have recently been browsed. Peer-to-peer search involves finding information in networks of nodes or computers without any centralized control. This type of search began as a file sharing tool for music but can be used in any community based on shared interests, or even shared locality in the case of mobile devices. Search and related information retrieval techniques are used for advertising, for intelligence analysis, for scientific discovery, for health care, for customer support, for real estate, and so on. Any application that involves a collection of text or other unstructured information will need to organize and search that information. In the next lesson, the business uses of the Internet, intranets, and extranets will be discussed.

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