URI

A Uniform Resource Identifier (URI) is a string that refers to a resource used by a web technology like a browser or an API.

Syntax

|----------------------------URL-------------------|
|        |--------------------------URN------------|------|
scheme://domain:port/path/to/resource?query=params#fragment
|----------------------------URI--------------------------|

URIs encompass the syntax of both URLs and URNs. It uses a scheme such as the HTTP protocol to describe how the resource is retrieved. This is followed by a domain that ends in something like “.com” or “.gov” and may also include a port number. Then, a file path is described along with any possible query params and page fragments.

Example

Codecademy has a page on Wikipedia, which contains a section about “Features”. The complete URI for this specific resource looks like this:

https://en.wikipedia.org/wiki/Codecademy#Features

The following is used in the example URI:

• A protocol scheme (https).
• A subdomain (en) that specifies the language for the site.
• The domain (wikipedia.org) containing the “.org” top-level domain.
• A directory to Codecademy’s wiki page (/wiki/Codecademy).
• A fragment (#Features) linking to a specific section in the page.