The unique address of a page is referred to as a Universal Resource Locator (URL). For example, the URL of this page is: http://www.ces.ncsu.edu/depts/it/itaids/publish/007/index.html There are three parts of a URL.
The first part: xxxx:// indicates the type of service or protocol for the file transfer. A few of the more common are:
- http - hypertext transfer protocol. Used for web pages.
- file - file transfer. Used to access files not on a web server, but on your system.
- ftp - file transfer protocol. Used for copying files from one system to another.
- telnet - telnet session. Used to obtain a login prompt on another system.
Currently, the most common service used in web pages is "http" for accessing (viewing) pages on a web server and "file" for accessing pages in your directory (not on a server yet).
The portion between the double slashes "//" and the following slash "/" indicates the server where the file (page) is stored. This page is on the "http://www.ces.ncsu.edu/" server. The server's name has three sections.
- hostname - The hostname is the name of the individual server. This page is in the "www" host.
- subdomain - The subdomain is the usually the name of the organization providing the internet connection and is located between the first and last dots (".").
- domain - The portion of the server's name after the last dot is domain. There are different domains for different types of organizations.
Following is a table of the more common domains and the type of organization they represent.
- edu - Educational institutions
- us - Regional network addresses in the United States (not very common)
- com - Commercial entities org Non-profit organizations
- net - Network providers
- gov - Government institutions
- mil - Military organizations
- cd - Canadian computing sites
- uk - United Kingdom computing sites
- au - Australian computing sites
Following the first single slash ("/") is the path to the directory where the file is stored. For this page, this is "depts/it/itaids/publish/007/". This path starts at the root directory of the web server not, the computer's file system.
The last part of the url is the filename of the document to be transferred. For this page the filename is "index.html". Most html (hypertext markup language) documents, which represent most static web pages, end in either ".htm", ".html" or ."shtml". If no filename is given, the server will look for a file in the directory specified named "index.html" or "index.shtml". If there is no file with that name in the directory, the browser may display a list of all the files and subdirectories in the directory specified or a "file not found" error page - depending on the web server's configuration.