Understanding Web Addresses

Think of the World Wide Web as a network of electronic files stored on millions of computers all around the world. Hypertext links these resources together. Uniform Resource Locators or URLs are the addresses used to locate the files. The information contained in a URL gives you the ability to jump from one web page to another with just a click of your mouse. When you type a URL into your browser or click on a hypertext link, your browser sends a request to a remote computer, called a web server, to download one or more files. Every URL is unique and identifies one specific file.

What does a typical URL look like? Here are a few examples:

http://www.learnthe net.com

The home page for Learn the Net.

ftp://rtfm.mit. edu/pub/

A directory of files at MIT available for downloading.

news:rec.gardens. roses

A newsgroup on rose gardening.

The first part of a URL (before the two slashes) tells you the type of resource or method of access at that address. For example:

• http - a hypertext document or directory
• gopher - a gopher document or menu
• ftp - a file available for downloading or a directory of these files
• news - a newsgroup
• telnet - a computer system that you can log into over the Internet
• WAIS - a database or document in a Wide Area Information Search database
• file - a file located on a local drive, for instance, the hard drive of your computer

The second part is typically the address of the computer where the data or service is located. Additional parts may specify the name of a file, the port to connect to, or the text to search for in a database

You enter the URL of a site by typing it into the Address bar of your web browser, located just under the toolbar.

Browsers can store the URLs that you want to revisit again by adding them to a special list. Netscape Navigator terms it Bookmarks; Microsoft Explorer terms it Favorites. Once you add a URL to your list, you return to that web page simply by clicking on the name in your list, instead of retyping the entire URL.

Most of the URLs you will use start with http, which stands for Hypertext Transfer Protocol, the method by which HTML files are transferred over the Web. Here are some other things to know about URLs:

• A URL usually has no spaces.
• A URL always uses forward slashes (//).
• If you type a URL incorrectly, your browser will not be able to locate the site or resource you want. Should you get an error message or access the wrong site, make sure you spelled the address correctly.
• You can find the URL behind any link by placing your cursor over the link. The pointer turns into a hand and the URL appears in your browser's status bar, usually located at the bottom of your browser window.

How the Web Works

The World Wide Web is the most popular part of the Internet by far. Once you spend time on the Web you will begin to feel like there is no limit to what you can discover. The Web allows rich and diverse communication by enabling you to access and interact with text, graphics, animation, photos, audio and video.

So just what is this miraculous creation? On the simplest level, the Web physically consists of your personal computer, web browser software, a connection to an Internet service provider, computers called servers that host digital data, and routers and switches to direct the flow of information.

The Web is known as a client-server system. Your computer is the client; the remote computers that store electronic files are the servers. Here's how it works:

Let's say you want to visit the the Louvre museum website. First you enter the address or URL of the website in your web browser (more about this shortly). Then your browser requests the web page from the web server that hosts the Louvre's site. The server sends the data over the Internet to your computer. Your web browser interprets the data, displaying it on your computer screen.

The Louvre's website also has links to the sites of other museums, such as the Vatican Museum. When you click on that link, you access the web server for the Vatican Museum. In this way, information scattered across the globe can be linked together.

The "glue" that holds the Web together is called hypertext and hyperlinks. This feature allows electronic files on the Web to be linked so you can jump easily between them. On the Web, you navigate through pages of information- -commonly known as browsing or surfing--based on what interests you at that particular moment.

To access the Web you need a web browser, such as Netscape Navigator or Microsoft Internet Explorer. How does your web browser distinguish between web pages and other types of data on the Internet? Web pages are written in a computer language called Hypertext Markup Language or HTML.