---
title: "Origin - Glossary | MDN"
chunk: 1/3
source: "https://developer.mozilla.org/en-US/docs/Glossary/Origin"
category: "reference"
tags: "web, html, css, javascript, documentation"
date_saved: "2026-05-05T05:39:30.254380+00:00"
instance: "kb-cron"
---

  * [Skip to main content](https://developer.mozilla.org/en-US/docs/Glossary/Origin#content)
  * [Skip to search](https://developer.mozilla.org/en-US/docs/Glossary/Origin#search)

[ MDN ](https://developer.mozilla.org/en-US/)
HTML
[HTML: Markup language](https://developer.mozilla.org/en-US/docs/Web/HTML) 

HTML reference
    
  * [Elements](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements)
  * [Global attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Global_attributes)
  * [Attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Attributes)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference "See all HTML references")

HTML guides
    
  * [Responsive images](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Responsive_images)
  * [HTML cheatsheet](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Cheatsheet)
  * [Date & time formats](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Date_and_time_formats)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides "See all HTML guides")

Markup languages
    
  * [SVG](https://developer.mozilla.org/en-US/docs/Web/SVG)
  * [MathML](https://developer.mozilla.org/en-US/docs/Web/MathML)
  * [XML](https://developer.mozilla.org/en-US/docs/Web/XML)

CSS
[CSS: Styling language](https://developer.mozilla.org/en-US/docs/Web/CSS) 

CSS reference
    
  * [Properties](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties)
  * [Selectors](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Selectors)
  * [At-rules](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/At-rules)
  * [Values](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference "See all CSS references")

CSS guides
    
  * [Box model](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Box_model/Introduction)
  * [Animations](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Animations/Using)
  * [Flexbox](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Flexible_box_layout/Basic_concepts)
  * [Colors](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Applying_color)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides "See all CSS guides")

Layout cookbook
    
  * [Column layouts](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Column_layouts)
  * [Centering an element](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Center_an_element)
  * [Card component](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Card)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook)

JavaScriptJS
[JavaScript: Scripting language](https://developer.mozilla.org/en-US/docs/Web/JavaScript) 

JS reference
    
  * [Standard built-in objects](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects)
  * [Expressions & operators](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators)
  * [Statements & declarations](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements)
  * [Functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference "See all JavaScript references")

JS guides
    
  * [Control flow & error handing](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Control_flow_and_error_handling)
  * [Loops and iteration](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Loops_and_iteration)
  * [Working with objects](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_objects)
  * [Using classes](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_classes)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide "See all JavaScript guides")

Web APIs
[Web APIs: Programming interfaces](https://developer.mozilla.org/en-US/docs/Web/API) 

Web API reference
    
  * [File system API](https://developer.mozilla.org/en-US/docs/Web/API/File_System_API)
  * [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
  * [Geolocation API](https://developer.mozilla.org/en-US/docs/Web/API/Geolocation_API)
  * [HTML DOM API](https://developer.mozilla.org/en-US/docs/Web/API/HTML_DOM_API)
  * [Push API](https://developer.mozilla.org/en-US/docs/Web/API/Push_API)
  * [Service worker API](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/API "See all Web API guides")

Web API guides
    
  * [Using the Web animation API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Animations_API/Using_the_Web_Animations_API)
  * [Using the Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch)
  * [Working with the History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API/Working_with_the_History_API)
  * [Using the Web speech API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Speech_API/Using_the_Web_Speech_API)
  * [Using web workers](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Using_web_workers)

All
[All web technology](https://developer.mozilla.org/en-US/docs/Web) 

Technologies
    
  * [Accessibility](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
  * [HTTP](https://developer.mozilla.org/en-US/docs/Web/HTTP)
  * [URI](https://developer.mozilla.org/en-US/docs/Web/URI)
  * [Web extensions](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions)
  * [WebAssembly](https://developer.mozilla.org/en-US/docs/WebAssembly)
  * [WebDriver](https://developer.mozilla.org/en-US/docs/Web/WebDriver)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web "See all web technology references")

Topics
    
  * [Media](https://developer.mozilla.org/en-US/docs/Web/Media)
  * [Performance](https://developer.mozilla.org/en-US/docs/Web/Performance)
  * [Privacy](https://developer.mozilla.org/en-US/docs/Web/Privacy)
  * [Security](https://developer.mozilla.org/en-US/docs/Web/Security)
  * [Progressive web apps](https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps)

Learn
[Learn web development](https://developer.mozilla.org/en-US/docs/Learn_web_development) 

Frontend developer course
    
  * [Getting started modules](https://developer.mozilla.org/en-US/docs/Learn_web_development/Getting_started)
  * [Core modules](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core)
  * [MDN Curriculum](https://developer.mozilla.org/en-US/curriculum/)
  * [Check out the video course from Scrimba, our partner](https://scrimba.com/frontend-path-c0j?via=mdn-learn-navbar)

Learn HTML
    
  * [Structuring content with HTML module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Structuring_content)

Learn CSS
    
  * [CSS styling basics module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Styling_basics)
  * [CSS layout module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/CSS_layout)

Learn JavaScript
    
  * [Dynamic scripting with JavaScript module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Scripting)

Tools
Discover our tools 
  * [Playground](https://developer.mozilla.org/en-US/play)
  * [HTTP Observatory](https://developer.mozilla.org/en-US/observatory)

  * [Border-image generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Border-image_generator)
  * [Border-radius generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Border-radius_generator)
  * [Box-shadow generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Box-shadow_generator)
  * [Color format converter](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Color_format_converter)
  * [Color mixer](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Color_mixer)
  * [Shape generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Shapes/Shape_generator)

About
Get to know MDN better 
  * [About MDN](https://developer.mozilla.org/en-US/about)
  * [Advertise with us](https://developer.mozilla.org/en-US/advertising)

  * [Community](https://developer.mozilla.org/en-US/community)
  * [MDN on GitHub](https://github.com/mdn)

[Blog](https://developer.mozilla.org/en-US/blog/)
  1. [Glossary](https://developer.mozilla.org/en-US/docs/Glossary)
  2. [Origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin)

# Origin
Web content's **origin** is defined by the _scheme_ (protocol), _hostname_ (domain), and _port_ of the [URL](https://developer.mozilla.org/en-US/docs/Glossary/URL) used to access it. Two objects have the same origin only when the scheme, hostname, and port all match.
Some operations are restricted to same-origin content, and this restriction can be lifted using [CORS](https://developer.mozilla.org/en-US/docs/Glossary/CORS).
## In this article
  * [Opaque origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin#opaque_origin)
  * [Examples](https://developer.mozilla.org/en-US/docs/Glossary/Origin#examples)
  * [See also](https://developer.mozilla.org/en-US/docs/Glossary/Origin#see_also)

##  [Opaque origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin#opaque_origin)
An opaque origin is a special type of browser-internal value that obscures the true origin of a resource (opaque origins are always serialized as `null`). They are used by the browser to ensure resource isolation as they are never considered equal to any other origin — including other opaque origins.
Opaque origins are applied in cases where the true origin of a resource is sensitive, cannot be safely used for security checks, or does not exist. A resource with an opaque origin will have its [`Origin`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Origin) HTTP header in requests set to [`null`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Origin#null). It will also fail same-origin checks with any other resource, and hence be restricted to only those operations available to cross-origin resources.
Common cases where opaque origins are used include:
  * A document within an iframe that has the [sandbox](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Security-Policy/sandbox) attribute set, and does not include the `allow-same-origin` flag.
  * `file:` URLs are usually treated as opaque origins so that files on the file system cannot read each other.
  * Documents created programmatically using APIs like [`DOMImplementation.createDocument()`](https://developer.mozilla.org/en-US/docs/Web/API/DOMImplementation/createDocument).

##  [Examples](https://developer.mozilla.org/en-US/docs/Glossary/Origin#examples)
These are same origin because they have the same scheme (`http`) and hostname (`example.com`), and the different file path does not matter:
  * `http://example.com/app1/index.html`
  * `http://example.com/app2/index.html`

These are same origin because a server delivers HTTP content through port 80 by default:
  * `http://example.com:80`
  * `http://example.com`

These are not same origin because they use different schemes:
  * `http://example.com/app1`
  * `https://example.com/app2`

These are not same origin because they use different hostnames:
  * `http://example.com`
  * `http://www.example.com`
  * `http://myapp.example.com`

These are not same origin because they use different ports:
  * `http://example.com`
  * `http://example.com:8080`

##  [See also](https://developer.mozilla.org/en-US/docs/Glossary/Origin#see_also)
  * [Same-origin policy](https://developer.mozilla.org/en-US/docs/Web/Security/Defenses/Same-origin_policy)
  * Related glossary terms: 
    * [Site](https://developer.mozilla.org/en-US/docs/Glossary/Site)
  * [HTML specification: origin](https://html.spec.whatwg.org/multipage/origin.html#origin)