Communication between computers

Networks
A network, simply put, is a collection of computers that communicate with each other. Like other forms of communication, there are certain elements that are necessary for two computers can talk. For two people can talk, you need a medium that information can pass through (air) and a way to encode and decode the information we want to send (the language). The physical medium for transmitting information in the case of a network is often a wire that connects the two computers, although wireless networks exist.

The languages used by computers to communicate are called communication protocols. Like languages in humans, there are several communication protocols (IPX, TCP / IP, NetBEUI, ATM, Myrinet are examples). The nuances of these protocols are unimportant in the context of this text. Just know that there are several, some protocols are better for certain tasks and two computers that do not use the same protocol simply can not exchange data.

The Internet
By having an understanding of what a network, it is much easier to define what the Internet. The Internet is a large global network. This network is so large that one is obliged to subdivide hierarchically. So basically, the Internet is rather a set of networks that are networked. These sub-networks can themselves be networks of networks. The machines that make up the Internet are extremely varied.

They range from the personal computer on which you connect to the University and huge routers that manage traffic. Unless voluntary isolation, any computer on the Internet can communicate with any other. There are however many millions of computers on the Internet that is all talk and not necessarily the same goals: John Doe is at home wants to check the weather on the Web while Ms. Doe is at work wants to transfer a document to his colleague and their son is at school wants to check his e-mail.

All these applications do not necessarily use the same communication protocol, but they are all based on a common basis. We can therefore say that there is a single standardized protocol for the Internet which can add other protocols for many applications that a transparent manner.

The World Wide Web
The Web is one of the many services offered on the Internet. This service is also so popular that many people make the mistake of confusing the Internet and the Web. The Web was designed to allow the presentation of multimedia documents. Thus, in addition to its textual content, the typical Web page presents the graphics and audio and video clips. The great advantage of the “WWW” lies in the fact that the user only has to pick through the document (commonly known as Web page) a hyperlink to new information that comes before him. In fact, the user does not have to worry about how the documents are recovered and transported to the terminal. That’s millions of pages about all possible subjects that become accessible to all.

The Web can be seen as a huge virtual library international: millions of shelves contain millions of books (websites). The books are arranged helter-skelter: you can not browse all the websites in a defined order. To find what we seek, we use search engines, Web sites that index the Web, which indicates that it is seeking and which we suggest places to visit. A lot of sites are created and maintained by companies that can use it as an advertising brochure, form, catalog, etc.. In the same way as a book, a website is a collection of pages, but unlike a book, the pages of a website are not necessarily in order.

To browse the Web, you should use a “browser”. The first graphical browser was born about 1990 and was called “WorldWideWeb.” Since then, dozens of sailors were launched. One of the most popular currently is undoubtedly Firefox. See section 4.1.1 for more information about browsers.

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