Wednesday, September 9, 2015

Introduction

The Internet is an integral part of our everyday lives. But if you are new to the online experience, it may be a bit overwhelming. You may be wondering, "What exactly is the Internet, and how does it work?"
In this lesson, we will give a brief overview of the Internet, and we will talk about some fundamental concepts such as networks, servers, and clients.

The Internet today
In the early days, most people just used the Internet to search for information. Today's Internet is a constantly evolving tool that not only contains an amazing variety of information but that also provides new ways of accessing, interacting, and connecting with people and content. As a result, new terms are constantly appearing.


What is the Internet?

The Internet is the largest computer network in the world, connecting millions of computers. A network is a group of two or more computer systems linked together.
There are two main types of computer networks:
  •  Local Area Network (LAN): A LAN is two or more connected computers sharing certain resources in a relatively small geographic location, often in the same building. Examples include home networks and office networks.
      


  •  Wide Area Network (WAN): A WAN typically consists of two or more LANs. The computers are farther apart and are linked by telephone lines, dedicated telephone lines, or radio waves. The Internet is the largest Wide Area Network (WAN) in existence.
 Servers and clients
You may have heard someone say something like "The server is down" or "We're having problems with the e-mail server." A server is a computer that "serves" many different computers in a network by running specialized software and storing information. For example, webpages are stored on servers.

When you access a webpage, your computer is acting as a client. A client runs familiar software such as web browsers or email software, and it communicates with the server to get the information it requires.

In order for your browser to display a webpage, it requests data from the server where the page is stored. The server processes the request, then sends the data to your browser, where it is displayed.


The World Wide Web

When most people think of the Internet, the first thing they think about is the World Wide Web. Nowadays, the terms "Internet" and "World Wide Web" are often used interchangeably—but they're actually not the same thing.
  • The Internet is the physical network of computers all over the world.
  • The World Wide Web is a virtual network of websites connected by hyperlinks (or "links"). Websites are stored on servers on the Internet, so the World Wide Web is a part of the Internet.






  • HTML
The backbone of the World Wide Web is made of HTML files, which are specially formatted documents that can contain links, as well as images and other media. All web browsers can read HTML files. In addition to HTML, it's common for websites to use technologies like CSS (Cascading Style Sheets) and JavaScript to do more advanced things. 
  • URL

To get to a webpage, you can type the URL (Uniform Resource Locator) into a browser. The URL, also known as the web address, tells the browser exactly where to find the page. However, most of the time, people get to a webpage by following a link from a different page or by searching for the page using a search engine. 

Did you know?

  • The foundation of the Internet began in 1969, when the U.S. Department of Defense created ARPAnet, a project to allow military personnel to communicate with each other in an emergency.
  • By 2012, the number of Internet users worldwide reached 2.4 billion—about one-third of the world's population.
  • To store all of the information that's available on the Internet, you would need more than 1 billion DVDs or 200 million Blu-ray discs.








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