kb/data/developer.mozilla.org/en-US/docs/Glossary/Site-0.md

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---
title: "Site - Glossary | MDN"
chunk: 1/3
source: "https://developer.mozilla.org/en-US/docs/Glossary/Site"
category: "reference"
tags: "web, html, css, javascript, documentation"
date_saved: "2026-05-05T05:45:23.953476+00:00"
instance: "kb-cron"
---
* [Skip to main content](https://developer.mozilla.org/en-US/docs/Glossary/Site#content)
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HTML
[HTML: Markup language](https://developer.mozilla.org/en-US/docs/Web/HTML)
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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)
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Topics
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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
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Tools
Discover our tools
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* [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)
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1. [Glossary](https://developer.mozilla.org/en-US/docs/Glossary)
2. [Site](https://developer.mozilla.org/en-US/docs/Glossary/Site)
# Site
Informally, a _site_ is a website, which is a collection of web pages, served from the same domain and maintained by a single organization, defined by its [registrable domain](https://developer.mozilla.org/en-US/docs/Glossary/Registrable_domain).
Browsers sometimes need to distinguish precisely between different sites. For example, the browser must only send [`SameSite`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Set-Cookie#samesitesamesite-value) cookies to the same site that set them.
For this more precise definition a site is determined by the _registrable domain_ portion of the domain name. The registrable domain consists of an entry in the [Public Suffix List](https://publicsuffix.org/list/) plus the portion of the domain name just before it. This means that, for example, `theguardian.co.uk`, `sussex.ac.uk`, and `bookshop.org` are all registrable domains.
According to this definition, `support.mozilla.org` and `developer.mozilla.org` are part of the same site, because `mozilla.org` is a registrable domain.
In some contexts, the scheme is also considered when differentiating sites. This would make `http://vpl.ca` and `https://vpl.ca` different sites. Including the scheme prevents an insecure (HTTP) site from being treated as the same site as a secure (HTTPS) site. A definition that considers the scheme is sometimes called a _schemeful same-site_. This stricter definition is applied in the rules for handling [`SameSite`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Set-Cookie#samesitesamesite-value) cookies.
**Note:** Browsers sometimes make security decisions (for example, deciding which resources a script can access) based on the [Origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin) of a resource. This is a more restrictive concept than the site, encompassing the scheme, the whole domain, and the port. See also [same-origin policy](https://developer.mozilla.org/en-US/docs/Web/Security/Defenses/Same-origin_policy).
## In this article
* [Examples](https://developer.mozilla.org/en-US/docs/Glossary/Site#examples)
* [See also](https://developer.mozilla.org/en-US/docs/Glossary/Site#see_also)
## [Examples](https://developer.mozilla.org/en-US/docs/Glossary/Site#examples)
These are the same site because the registrable domain of `mozilla.org` is the same:
* `https://developer.mozilla.org/en-US/docs/`
* `https://support.mozilla.org/en-US/`
These are considered the same site because the port number is ignored when determining the site:
* `https://example.com:8080`
* `https://example.com`
These are not the same site because the registrable domain of the two URLs differs:
* `https://developer.mozilla.org/en-US/docs/`
* `https://example.com`
These are the same site, or different sites if the scheme is considered:
* `http://example.com`
* `https://example.com`
## [See also](https://developer.mozilla.org/en-US/docs/Glossary/Site#see_also)
* [What is a URL](https://developer.mozilla.org/en-US/docs/Learn_web_development/Howto/Web_mechanics/What_is_a_URL)
* Related glossary terms:
* [Origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin)
* [Registrable domain](https://developer.mozilla.org/en-US/docs/Glossary/Registrable_domain)
* [Same-origin policy](https://developer.mozilla.org/en-US/docs/Web/Security/Defenses/Same-origin_policy)