URL stands for Unique Resource Locator. It is the unique address of a page or piece of digital content on the Internet. The URL of a page can be found in the navigation bar of a browser window as shown below:
URL Examples
"Aunt Sue, you can access my website by typing the URL into your browser."
"The URL for Google's homepage is www.Google.com."
History of Uniform Resource Locators
URL was defined in 1994 in Request for Comments (RFC) by Tim Berners-Lee, whom invented the World Wide Web. Before URL, other conventions existed. URL combined two former conventions to include domain names followed by file paths. Berners-Lee later expressed regret of the use of periods and the colon in the URL.
Syntax of a URL
URLs can be made up of several parts, some being required, others optional. These parts are the scheme, authority component, path, query and fragment.
Most URLs starts with a scheme such as http, https or ftp. Every scheme is followed by a colon (:). Following schemes with an authority component (explained below) is two forward slashes (//).
Some URLs have an authority component that has a host such as a domain name, server name or IP address.
All URLs have a path starting with a single forward slash. A path may follow an authority component or a scheme. A path may be implied or empty (as seen on many website's homepages). A path typically ends with a file. Sometimes files may be implied, such as the index file on websites that may or may not appear in the URL.
Following a path, there could be an optional query or fragment. Queries follow a path and begin with a question mark (?) and contain attributes, followed by an equals sign (=), and values. Multiple queries would be separated by commas (,) or ampersands (&). Fragments may follow a path and begin with a hash (#) and contain a secondary direction within the same path location. On HTML documents (websites), the fragment often points to an id attribute located on that page.
e.g. scheme://authority.component/path/file.html?query=value#fragment