Uniform Resource Identifiers

Overview

A uniform resource identifier (URI) is a unique sequence of characters for identifying some physical or abstract resource. URIs are further generalized to internationalized resource identifiers (IRIs) which allow using characters from any language, provided there exists a standard web encoding of the characters.

The URI generic syntax consists of five components organized hierarchically in order of decreasing significance from left to right:

<scheme>:[//<authority>]<path>[?<query>][#<fragment>]

where the <authority> is further composed as

[<userinfo>@]<host>[:<port>]

URLs

A uniform resource locator (URL) is a URI that specifies the means of finding the represented resource. The most commonly used schemes are http and https.

URNs

A uniform resource name (URN) is a URI that uses the urn scheme. It is intended to uniquely identify a resource, even when the resource no longer exists.

CURIEs

A compact URI (CURIE) is a denser representation of IRIs. In its simplest form, it consists of a prefix and reference, separated by a colon. For example, geo:England.