URIs | MDN

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URIs

Uniform Resource Identifiers (URI) are used to identify "resources" on the web. URIs are commonly used as targets of HTTP requests, in which case the URI represents a location for a resource, such as a document, a photo, binary data. The most common type of URI is a Uniform Resource Locator (URL), which is known as the web address.
URIs can be used to trigger behaviors other than fetching a resource, including opening an email client, sending text messages, or executing JavaScript, when used in other places such as the href of an HTML <a> link.

Reference

The URI reference provides details about the components that make up a URI.
Schemes
The first part of the URI, before the : character, which indicates the protocol the browser must use to fetch the resource.
Authority
The section that comes after the scheme and before the path. It may have up to three parts: user information, host, and port.
Path
The section after the authority. Contains data, usually organized in hierarchical form, to identify a resource within the scope of the URI's scheme and authority.
Query
The section after the path. Contains non-hierarchical data to identify a resource within the scope of the URI's scheme and naming authority along with data in the path component.
Fragment
An optional part at the end of a URI starting with a # character. It is used to identify a specific part of the resource, such as a section of a document or a position in a video.

Guides

The URI guides help you work with URIs on the web.
Choosing between www and non-www URLs
Guidance on when sites should use a www. prefix in URLs (www.example.com vs example.com).

Specifications

Specification
Unknown specification​ (external)

See also

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