What is a URL?
Uniform Resource Locator (URL), commonly known as a Web address, is a reference to a Web resource, which specifies its location on a computer network and the mechanism for retrieving it. URL is a specific type of Uniform Resource Identifier (URI), although many people use the two terms interchangeably. URLs are most commonly used to refer to web pages (http), but are also used for file transfer (ftp), e-mail (mailto), database access (JDBC) and many other applications.
Most web browsers display the URL of the web page at the top of the page in the address bar. A typical URL can take the form of http://www.example.com/ index.html, which represents the protocol (http), host name (www.example.com) and file name (index.html).
The inventor of the Internet Tim Berners-Lee and the URI Working Group of the Internet Engineering Task Force (IETF) defined Uniform Resource Locator in RFC 1738 in 1994.
This is from the IETF The collaboration started by Living Documents resulted in the 1992 feather competition. This format combines the domain name system (created in 1985) with file path syntax, where slashes are used to separate directory and file names. The convention already exists. You can prefix the server name with the full file path, and add a double slash (//) before it.
Berners-Lee later expressed regret about the use of dots to separate the various parts of the domain name in the URI, and hoped that he used slashes throughout the text, and also said that since the colon is located after the first component of the URI , So add two slashes before the domain name. The domain name is unnecessary.