Understanding Web Addresses

　　You can think of the World Wide Web as a network of electronic files stored on computers all around the world. Hypertext links these resources together. Uniform Resource Locators or URLs are the addresses used to locate these 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 is sending a request to a remote computer to download a file.

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

　　http://english.chinaschool.net

　　The home page for study english.

　　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 such 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 （your hard drive）

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

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

　　Most browsers record URLs that you want to use again， by adding them to a special menu. In Netscape Navigator， it's called Bookmarks. In Microsoft Explorer， it's called Favorites. Once you add a URL to your list， you can 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 be using start with http which stands for Hypertext Transfer Protocol*. http is the method by which HTML files are transferred over the Web. Here are some other important things to know about URLs：

　　A URL usually has no spaces.

　　A URL always uses forward slashes （//）。

　　If you enter a URL incorrectly， your browser will not be able to locate the site or resource you want. Should you get an error message or the wrong site， make sure you typed the address correctly.

　　You can find the URL behind any link by passing your mouse cursor over the link. The pointer will turn into a hand and the URL will appear in the browser's status bar， usually located at the bottom of your screen.

　　注释：

　　MIT：Massachusettes Institute of Technology （美国）麻省理工学院

　　slash：斜线

　　WAIS： Wide Area Information Server 广域信息服务系统

　　Hypertext Transfer Protocol：超文本传输协议