The Free On-line Dictionary of Computing (19 January 2023):

Universal Resource Identifier
URI

    (URI, originally "UDI" in some WWW
   documents) The generic set of all names and addresses which
   are short strings which refer to objects (typically on the
   Internet).  The most common kinds of URI are URLs and
   relative URLs.

   URIs are defined in RFC 1630.

   W3 specification
   (http://w3.org/hypertext/WWW/Addressing/URL/URI_Overview.html).

   (1997-07-16)