URIs | MDN * Skip to main content * Skip to search HTML HTML: Markup language HTML reference * Elements * Global attributes * Attributes * See all… HTML guides * Responsive images * HTML cheatsheet * Date & time formats * See all… Markup languages * SVG * MathML * XML CSS CSS: Styling language CSS reference * Properties * Selectors * At-rules * Values * See all… CSS guides * Box model * Animations * Flexbox * Colors * See all… Layout cookbook * Column layouts * Centering an element * Card component * See all… JavaScript JS JavaScript: Scripting language JS reference * Standard built-in objects * Expressions & operators * Statements & declarations * Functions * See all… JS guides * Control flow & error handing * Loops and iteration * Working with objects * Using classes * See all… Web APIs Web APIs: Programming interfaces Web API reference * File system API * Fetch API * Geolocation API * HTML DOM API * Push API * Service worker API * See all… Web API guides * Using the Web animation API * Using the Fetch API * Working with the History API * Using the Web speech API * Using web workers All All web technology Technologies * Accessibility * HTTP * URI * Web extensions * WebAssembly * WebDriver * See all… Topics * Media * Performance * Privacy * Security * Progressive web apps Learn Learn web development Frontend developer course * Getting started modules * Core modules * MDN Curriculum * Check out the video course from Scrimba, our partner Learn HTML * Structuring content with HTML module Learn CSS * CSS styling basics module * CSS layout module Learn JavaScript * Dynamic scripting with JavaScript module Tools Discover our tools * Playground * HTTP Observatory * Border-image generator * Border-radius generator * Box-shadow generator * Color format converter * Color mixer * Shape generator About Get to know MDN better * About MDN * Advertise with us * Community * MDN on GitHub Blog Toggle sidebar * Web * URIs Theme * OS default * Light * Dark English (US) Remember language Learn more * Deutsch * English (US) * Français * 日本語 * 한국어 * Русский * 中文 (简体) 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. In this article * Reference * Guides * Specifications * See also 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 See also * What is a URL? Help improve MDN Yes No Learn how to contribute This page was last modified on Jun 22, 2026 by MDN contributors . View this page on GitHub • Report a problem with this content Clear filter input * URIs * Guides * Using 'www' in URLs * Reference * Scheme * blob: * data: * javascript: * resource: * urn: * Authority * Path * Query * Fragment * Media fragments * Text fragments Your blueprint for a better internet. * * * * * MDN * About * Blog * Mozilla careers * Advertise with us * MDN Plus * Product help Contribute * MDN Community * Community resources * Writing guidelines * MDN Discord * MDN on GitHub Developers * Web technologies * Learn web development * Guides * Tutorials * Glossary * Hacks blog * Website Privacy Notice * Telemetry Settings * Legal * Community Participation Guidelines Portions of this content are ©1998–2026 by individual mozilla.org contributors. Content available under a Creative Commons license .