Uniform Resource Locator (URL) has two meanings. URL is a synonym for Uniform Resource Identifier (URI) and most people will use URL instead of URI.
URI, which makes more sense than the popular URL, is a global identifier for the World Wide Web. In its current strict technical meaning, a URL is a URI that, “in addition to identifying a resource, [provides] a means of locating the resource by describing its primary access mechanism (e.g., its network ‘location’).
A URL is written into your favorite Web Browser in the address bar like this: