RFC 2396 (rfc2396) - Page 2 of 40

Uniform Resource Identifiers (URI): Generic Syntax

RFC 2396                   URI Generic Syntax                August 1998


1. Introduction

   Uniform Resource Identifiers (URI) provide a simple and extensible
   means for identifying a resource.  This specification of URI syntax
   and semantics 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 URI is designed to meet the
   recommendations laid out in "Functional Recommendations for Internet
   Resource Locators" [RFC 1736] and "Functional Requirements for Uniform
   Resource Names" [RFC 1737].

   This document updates and merges "Uniform Resource Locators"
   [RFC 1738] and "Relative Uniform Resource Locators" [RFC 1808] in order
   to define a single, generic syntax for all URI.  It excludes those
   portions of RFC 1738 that defined the specific syntax of individual
   URL schemes; those portions will be updated as separate documents, as
   will the process for registration of new URI schemes.  This document
   does not discuss the issues and recommendation for dealing with
   characters outside of the US-ASCII character set [ASCII]; those
   recommendations are discussed in a separate document.

   All significant changes from the prior RFCs are noted in Appendix G.

1.1 Overview of URI

   URI are characterized by the following definitions:

      Uniform
         Uniformity provides several benefits: it allows different types
         of resource identifiers to be used in the same context, even
         when the mechanisms used to access those resources may differ;
         it allows uniform semantic interpretation of common syntactic
         conventions across different types of resource identifiers; it
         allows introduction of new types of resource identifiers
         without interfering with the way that existing identifiers are
         used; and, it allows the identifiers to be reused in many
         different contexts, thus permitting new applications or
         protocols to leverage a pre-existing, large, and widely-used
         set of resource identifiers.

      Resource
         A resource can be anything that has identity.  Familiar
         examples include an electronic document, an image, a service
         (e.g., "today's weather report for Los Angeles"), and a
         collection of other resources.  Not all resources are network
         "retrievable"; e.g., human beings, corporations, and bound
         books in a library can also be considered resources.



Berners-Lee, et. al.        Standards Track