Uniform Resource Locator (URL)

What is a URL?
A Uniform Resource Locator (URL) is used to designate a location address for a web page within the World Wide Web. URL's were defined by Tim Berners-Lee in 1994 in response to the need for online resource collaboration between individuals in two remote locations.

Syntax
"scheme:[//[user[:password]@]host[:port]][/path][?query][#fragment]|undefined"
 * Scheme: a sequence of characters beginning with a letter and followed by any combination of letters, digits, etc.
 * An authority part consisting of
 * An authentication section or username
 * A host consisting of either a registered name or IP address
 * An optional port number, separated by a semi-colon

Source: https://en.wikipedia.org/wiki/URL#CITEREFBBC_News2009
 * A path which contains data organized in a hierarchical format.
 * An optional query conmtaining a query string
 * an optional fragment containing a fragment identifier