Common confusion right? Let’s see:
URIs are a standard for identifying documents using a short string of numbers, letters, and symbols. They are defined by RFC 3986 – Uniform Resource Identifier (URI): Generic Syntax. URLs, URNs, and URCs are all types of URI.
Contains information about how to fetch a resource from its location. For example:
URLs always start with a protocol (
http) and usually contain information such as the network host name (
example.com) and often a document path (
/foo/mypage.html). URLs may have query parameters and fragment identifiers.
Identifies a resource by a unique and persistent name, but doesn’t necessarily tell you how to locate it on the internet. It usually starts with the prefix
urn: For example:
urn:isbn:0451450523 to identify a book by its ISBN number.
urn:uuid:6e8bc430-9c3a-11d9-9669-0800200c9a66 a globally unique identifier
urn:publishing:book – An XML namespace that identifies the document as a type of book.
URNs can identify ideas and concepts. They are not restricted to identifying documents. When a URN does represent a document, it can be translated into a URL by a “resolver”. The document can then be downloaded from the URL.
URC — Uniform Resource Citation
Points to meta data about a document rather than to the document itself. An example of a URC is one that points to the HTML source code of a page like:
Rather than locating it on the internet, or naming it, data can be placed directly into a URI. An example would be