Network Working Group T. Berners-Lee
Request for Comments: 1738 CERN
Category: Standards Track L. Masinter
University of Minnesota
Uniform Resource Locators (URL)
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
This document specifies a Uniform Resource Locator (URL), the syntax
and semantics of formalized information for location and access of
resources via the Internet.
This document describes the syntax and semantics for a compact string
representation for a resource available via the Internet. These
strings are called "Uniform Resource Locators" (URLs).
The specification is derived from concepts introduced by the World-
Wide Web global information initiative, whose use of such objects
dates from 1990 and is described in "Universal Resource Identifiers
in WWW", RFC 1630. The specification of URLs is designed to meet the
requirements laid out in "Functional Requirements for Internet
Resource Locators" .
This document was written by the URI working group of the Internet
Engineering Task Force. Comments may be addressed to the editors, or
to the URI-WG <email@example.com>. Discussions of the group are archived
RFC 1738 Uniform Resource Locators (URL) December 1994
2. General URL Syntax
Just as there are many different methods of access to resources,
there are several schemes for describing the location of such
The generic syntax for URLs provides a framework for new schemes to
be established using protocols other than those defined in this
URLs are used to `locate' resources, by providing an abstract
identification of the resource location. Having located a resource,
a system may perform a variety of operations on the resource, as
might be characterized by such words as `access', `update',
`replace', `find attributes'. In general, only the `access' method
needs to be specified for any URL scheme.
2.1. The main parts of URLs
A full BNF description of the URL syntax is given in Section 5.
In general, URLs are written as follows:
A URL contains the name of the scheme being used () followed
by a colon and then a string (the <scheme-specific-part>) whose
interpretation depends on the scheme.
Scheme names consist of a sequence of characters. The lower case
letters "a"--"z", digits, and the characters plus ("+"), period
("."), and hyphen ("-") are allowed. For resiliency, programs
interpreting URLs should treat upper case letters as equivalent to
lower case in scheme names (e.g., allow "HTTP" as well as "http").
2.2. URL Character Encoding Issues
URLs are sequences of characters, i.e., letters, digits, and special