1. Introduction

1. Introduction

This specification defines a Uniform Resource Name namespace for Universally Unique IDentifiers (UUIDs), also known as Globally Unique IDentifiers (GUIDs). A UUID is 128 bits long and requires no central registration process.

The use of UUIDs is extremely pervasive in computing. They comprise the core identifier infrastructure for many operating systems such as Microsoft Windows and applications such as the Mozilla Web browser; in many cases, they can become exposed in many non-standard ways.

This specification attempts to standardize that practice as openly as possible and in a way that attempts to benefit the entire Internet. The information here is meant to be a concise guide for those wishing to implement services using UUIDs either in combination with URNs [RFC8141] or otherwise.

There is an ITU-T Recommendation and an ISO/IEC Standard [X667] that are derived from [RFC4122]. Both sets of specifications have been aligned and are fully technically compatible. Nothing in this document should be construed to override the DCE standards that defined UUIDs.