What is a URL (or URI)?
A Uniform Resource Locator (URL) is the string of letters that define the ‘location’ of a resource and how to get to it e.g. http://www.mydomain.com is conventionally a web service for mydomain.com using the HTTP protocol (will contain HTML). The URL is used (resolved) by a DNS and an IP address returned from an authoritative DNS for the domain. A Uniform Resource Identifier (URI) is subtly different and is a string of letters that defines the identity of a resource and which also, usually, includes its location e.g. in a URI of http://www.zytrax.com/isp/index.htm, the URL part is http://www.zytrax.com/isp/. A URL is always a subset of a URI.
