A URL, or Uniform Resource Locator, is the method by which resources on the internet can be located and navigated to. In practice, a URL is the entire web address of a given webpage, including the initial portion.
For instance, while the URI of a website might be “images.facebook.com“, the full URL must include the initial section of their web address: “http://images.facebook.com“. That’s because that initial portion of the web address details how the browser should access the webpage, which is an important part of how URLs are designed to communicate.