What Is a URL?
It's often easiest, although not entirely accurate, to think of a URL as the name of a file on the World Wide Web because most URLs refer to a file on some machine on the network. However, remember that URLs also can point to other resources on the network, such as database queries and command output.
Definition: URL is an acronym for Uniform Resource Locator and is a reference (an address) to a resource on the Internet.
The following is an example of a URL which addresses the
java.sun.com website:
- Protocol identifier
- Resource name
The resource name is the complete address to the resource. The format of the resource name depends entirely on the protocol used, but for many protocols, including HTTP, the resource name contains one or more of the components listed in the following table:
| Host Name | The name of the machine on which the resource lives. |
|---|---|
| Filename | The pathname to the file on the machine. |
| Port Number | The port number to which to connect (typically optional). |
| Reference | A reference to a named anchor within a resource that usually identifies a specific location within a file (typically optional). |
For many protocols, the host name and the filename are required, while
the port number and reference are optional. For example, the resource
name for an HTTP URL must specify a server on the network (Host Name)
and the path to the document on that machine (Filename); it also can
specify a port number and a reference. In the URL for the Java Web
site java.sun.com is the host name
and an empty path or the trailing slash is shorthand for
the file named /index.html.
