This website provides Mozilla product documentation written by the user community. You can follow the links below to browse all of the articles, or use th…

Mozilla is a global non-profit dedicated to putting you in control of your online experience and shaping the future of the web for the public good. Visit …

A product is first an idea, then a project, and then a prototype. Here, at Mozilla, our awesome community is there every step of the way to support and co…

This article is in parts, or in its entirety, outdated. Hence, the information presented on this page may be incorrect, and should be treated with due cau…

By the time a kid turns 13, more than 72 million pieces of personal data have been collected about them on the internet, according to a 2018 report. These…

means each individual or legal entity that creates, contributes to the creation of, or owns Covered Software. 1.2. “Contributor Version” means the combina…

Mozilla operates under a module ownership governance system . A module is a discrete unit of code or activity. An owner is the person in charge of a modul…

Mozilla’s CA Certificate Program governs inclusion of root certificates in Network Security Services (NSS), a set of open source libraries designed to sup…

The heart of Mozilla is people. We put people first and do our best to recognize, appreciate and respect the diversity of our global contributors. The Moz…

When distributing binary and source code versions of Firefox, Thunderbird, and other Mozilla-related software products, Mozilla may include with such soft…

Cookies are small pieces of textual information stored by webpages on your computer. Their many uses include remembering login information and preserving …

Mozilla Release Drivers are the group of individuals that are entrusted with the coordination of Firefox releases, formally defined by membership in the m…

Rust support has been required on all platforms since Firefox 54, and the first major Rust components were shipped in Firefox 56 (encoding_rs) and 57 (Sty…

Pootle a web server for localisation that allows web-based contributions and management. Combined with the Translate Toolkit it allows Mozilla products t…

Privacy on the web is not well controlled by the user. There are cases where the user has explicit and desired relationships with sites (or, in the broade…

This article addresses the use of relative "em" and "ex" units in CSS, which can potentially cause rendering problems due to pixel rounding errors . Read …

The correct title of this article is about:config . It appears incorrectly here due to technical limitations in the wiki software. about:config is a featu…

The Thunderbird Council is the elected governing body for the Thunderbird Project , including the code modules that develop the code in Thunderbird produc…

Mozilla uses GeckoView to power Firefox for Android , Firefox Reality , Firefox Focus , and other Android apps. GeckoView serves a similar purpose to Andr…

Mozilla Thunderbird 2.0.0.4 was released on Thursday 14th June. This update to the Mozilla Corporation's mail client includes bug fixes but no new feature…

(5/1/2018) The Electrolysis Project is officially complete. Mozilla continues to work on scaling the Gecko process model through newer projects and work, …

The open, global internet is the most powerful communication and collaboration resource we have ever seen. It embodies some of our deepest hopes for human…

⚡ Warning: The content of this page is obsolete and kept for archiving purposes of past processes. These pages on wiki.mozilla.org are about XULRunner dev…

NOTE: this page has been made obsolete and is no longer maintained. For up to date information on Mozilla's strategy, AI work, OKRs and more, please visit…

Please note: the API is called "WebExtensions" because it can be found in search engines; "Web Extensions" (with a space) does not yield relevant results.…

The Password Manager can be used to automatically fill in the username/password needed to access web sites and log into mail servers. However, it stores t…

The EFF published an excellent study in May, detailing some of the various methods of fingerprinting a browser. See http://www.eff.org/deeplinks/2010/05/e…

Get all the speed and tools with none of the invasions of privacy. Firefox Browser collects so little data about you, we don’t even require your email add…

In Bugzilla, almost every patch that is submitted goes through a process of review, where it is looked at by an experienced Bugzilla developer to make sur…

Firefox is a key expression of Mozilla's mission and manifesto ; it represents our vision of a people-centric web experience, as well as a platform and to…

A protocol is a method that is used to send, receive, and handle information over a connection. Common protocols viewed from the browser include http , ht…

To get more information or talk to a human, or just to introduce yourself, see Thunderbird Communication Channels , especially the IRC channel. Again, we …

SVG Fonts address some use-cases which cannot be addressed using current OpenType-based solutions. For example: Editable text where the glyphs display a "…

This article describes how to prevent specific settings from being modified from inside Firefox, Thunderbird, or SeaMonkey. This is commonly known as lock…

By default Thunderbird and Seamonkey display the time only (without the date) for messages with today's date. For messages older than this, they display b…

Determine which root certificates should be included in Mozilla software products, which trust bits should be set on them, and which of them should be ena…

Whether you're technical or not at all, there's a contribution opportunity for you. It's easy to get started, and your efforts help to make Firefox better!

Get all the speed and tools with none of the invasions of privacy. Firefox Browser collects so little data about you, we don’t even require your email add…

Some websites require the use of the Windows Media Player (WMP) plugin for certain content such as embedded audio and video. This article describes how to…

The font-palette CSS property allows specifying one of the many palettes contained in a font that a user agent should use for the font. Users can also ov…

Do not automatically fill sign-in forms with known usernames and passwords; instead, act as though there are multiple usernames/password pairs remembered …

The installation directory is the directory where a Mozilla application stores its program files. It is usually a directory on your own computer. This app…

If you want a bug that is related to memory usage to be triaged in a MemShrink meeting, add "[MemShrink]" to the bug whiteboard. After prioritization, thi…

This schedule is based on the current RapidRelease plan. Future dates may change if the process changes. Code is not always released to users on the same …

This article is in parts, or in its entirety, outdated. Hence, the information presented on this page may be incorrect, and should be treated with due cau…

Firefox stores a user's personal information such as bookmarks, extensions, and user preferences in a unique profile . The first time you start Firefox, i…

URLs of the form /r/<id>/diff/[<revision>/] redirect to the associated commit in the review-repo archive . Note that, at the moment, all revisions of a gi…

This will make us the second/third browser to ship this, enabling more web developers to use it. That is, this helps with web compatibility and moves the …

A map of the skills and competencies people need to read, write and participate effectively on the web. Important note: Mozilla's Web Literacy Map was co-…

If you plan on presenting, please join the Zoom video chat 20 minutes prior to the start of the meeting and announce to the A/V Technicians that you will…

What is in this minimum policy? Is this automatic? If it is, can the author override it? How does this work with resources on CDNs and other domains? Is t…

In a market where changes constantly happen, 5 months is a long time for a feature to wait to be in an official build. I think this is going to push more…

First Look at Firefox-Based Netscape The Netscape Browser prototype is based on Mozilla Firefox 0.9.3. Netscape are very careful to use the term 'prototy…

This page discusses incidents, incident reporting, remediation, and communication. It gives guidance to CAs as to how Mozilla expects them to react to rep…

This document describes the minimum set of policy requirements that a party must satisfy to be considered as a potential partner for Mozilla’s Trusted Rec…

HTTP is the application-layer protocol with which most web pages are transferred. As part of HTTP, requests can include a "Referer" (sic) header that tell…

GNU/Linux Firefox uses the GTK setting to determine whether Emacs-like/Readline-like keybindings are active in text fields. There are two different metho…

This preference controls whether to use a pop-up alert or an error page for sites that can't be loaded because of a network problem. Possible values and t…

Give a man a fish, and he eats for a day. Teach a man to fish , and he eats for a lifetime. I like poetry, long walks on the beach and poking dead thing…

Think for yourself. Otherwise you have to believe what other people tell you. A society based on individualism is an oxymoron. || Freedom is at first th…

It is very common for IMAP users, especially those migrating from other clients, to delete their messages by "Mark it as deleted" instead of "Move it to …

Add your name and accomplishments under the appropriate month (please be specific). We choose an outstanding contributor ( Friend of Add-ons ) about once …

Contents Goals The problem is that right now our end to end time from checkin to all tests done is around 6-8 hours. That's wasting a lot of developer ti…

i ve been getting http://www.superfish .com blank page opening up on my firefox 3.6.8 lately , which is slowing down and blocking my access to other pages…

Since I installed 0.9 I have been having problems with the following: I have an email (Thunderbird 0.6) that has an ASP link to an order I made at compu…

<u><b>--== UPDATE / WORKAROUND FOR WINDOWS 95/98/ME/2000/XP ==--</b></u> This is now a known bug in bugtraq. It appears that Firefox 0.9 doesn't registe…

Seriosuly who reads to the bottom of this page anyway hoping to find something for their PPC machine ? Will anyone ever realize there are PPC releases ava…

SVG: Scalable Vector Graphics As such, it's a text-based, open Web standard for describing images that can be rendered cleanly at any size and are design…

In this article In this article Web APIs When writing code for the Web, there are a large number of Web APIs available. Below is a list of all the APIs a…

I discovered this 'feature' of Thunderbird when I had a client ask me to migrate him from Thunderbird to Outlook 2003 (keep reading and keep your politica…

In this article HTML: HyperText Markup Language HTML (HyperText Markup Language) is the most basic building block of the Web. It defines the meaning and …

When local HTML files (e.g., those located on your hard drive) are loaded into the browser, the scripts and links within have restrictions on what they ca…

Browse to the folder containing the bookmarks HTML file, select the file you wish to import and click "open". The imported bookmarks will be added to your…

In this article In this article Event reference Events are fired to notify code of "interesting changes" that may affect code execution. These can arise …

If you don't want to get a Github account, you can still clone the repository, but you won't be able to push upstream or issue pull requests: git clone h…

In this article WebAssembly WebAssembly is a new type of code that can be run in modern web browsers — it is a low-level assembly-like language with a co…

After upgrading to 3.6b4, i can't use my corporate proxy server anymore. It requires ntlm authentication and firefox does not seem to handle it correctly…

The FSA Executive Board is a dedicated collection of Mozilla Reps and passionate community volunteers who serve as leaders in the Student Ambassador progr…

CSP is designed to be fully backward compatible (except CSP version 2 where there are some explicitly-mentioned inconsistencies in backward compatibility;…

Web app manifests are deployed in your HTML pages using a <link> element in the <head> of a document: html <linkrel="manifest"href="manifest.json"/> The …

Cross-Origin Resource Sharing ( CORS ) is an HTTP -header based mechanism that allows a server to indicate any origins (domain, scheme, or port) other tha…

I'm on a Windows 7 (64-bit) desktop. Since upgrading to Firefox 6, I've noticed that Firefox will sometimes stop loading all web pages. I am able to cons…

This section is dedicated to the JavaScript language itself, and not the parts that are specific to Web pages or other host environments. For information…

By default, JavaScript is not allowed to read or set your clipboard data for security and privacy reasons. This is because websites scripts can erase and …

Asynchronously loads a page from the session history, identified by its relative location to the current page, for example -1 for the previous page or 1 f…

This page contains information about the community and how to reach out. Warning References below this point are part of the deprecated documentation and …

In this article WebGL: 2D and 3D graphics for the web WebGL (Web Graphics Library) is a JavaScript API for rendering high-performance interactive 3D and …

In this article Browser extensions Extensions, or add-ons, can modify and enhance the capability of a browser. Extensions for Firefox are built using the…

In this article Performance The Performance interface provides access to performance-related information for the current page. An object of this type can…

I am deeply honored and humbled by the CEO role. I’m also grateful for the messages of support. At the same time, I know there are concerns about my commi…

This article explains how to open multiple instances of your Mozilla application at the same time, using different profiles. It was written for Firefox bu…

Programming languages all have built-in data structures, but these often differ from one language to another. This article attempts to list the built-in d…

The same-origin policy is a critical security mechanism that restricts how a document or script loaded by one origin can interact with a resource from ano…

This morning, Adobe announced its roadmap to stop supporting Flash at the end of 2020. Working with Adobe and other browser vendors, Mozilla has prepared …

Subresource Integrity (SRI) is a security feature that enables browsers to verify that resources they fetch (for example, from a CDN ) are delivered witho…

Nearly all objects in JavaScript are instances of Object ; a typical object inherits properties (including methods) from Object.prototype , although these…

A Promise is a proxy for a value not necessarily known when the promise is created. It allows you to associate handlers with an asynchronous action's even…

MozCamp Contents What Is MozCamp? MozCamps are a critical part of our Grow Mozilla program, aiming to mentor and train core contributors to help us bring…

Functions created with the Function constructor do not create closures to their creation contexts; they always are created in the global scope. When runni…

Contents Background CSS can use a variety of units for specifying dimensions. These units are classified as either absolute or relative. Absolute units (…

The Mozilla Monster Although i continue to recommend the Firefox web browser for technical reasons, i hold nothing but contempt for the Mozilla corporatio…

This website provides Mozilla product documentation written by the user community. You can follow the links below to browse all of the articles, or use th…

Mozilla is a global non-profit dedicated to putting you in control of your online experience and shaping the future of the web for the public good. Visit …

A product is first an idea, then a project, and then a prototype. Here, at Mozilla, our awesome community is there every step of the way to support and co…

This article is in parts, or in its entirety, outdated. Hence, the information presented on this page may be incorrect, and should be treated with due cau…

By the time a kid turns 13, more than 72 million pieces of personal data have been collected about them on the internet, according to a 2018 report. These…

means each individual or legal entity that creates, contributes to the creation of, or owns Covered Software. 1.2. “Contributor Version” means the combina…

Mozilla operates under a module ownership governance system . A module is a discrete unit of code or activity. An owner is the person in charge of a modul…

Mozilla’s CA Certificate Program governs inclusion of root certificates in Network Security Services (NSS), a set of open source libraries designed to sup…

The heart of Mozilla is people. We put people first and do our best to recognize, appreciate and respect the diversity of our global contributors. The Moz…

When distributing binary and source code versions of Firefox, Thunderbird, and other Mozilla-related software products, Mozilla may include with such soft…

Cookies are small pieces of textual information stored by webpages on your computer. Their many uses include remembering login information and preserving …

Mozilla Release Drivers are the group of individuals that are entrusted with the coordination of Firefox releases, formally defined by membership in the m…

Rust support has been required on all platforms since Firefox 54, and the first major Rust components were shipped in Firefox 56 (encoding_rs) and 57 (Sty…

Pootle a web server for localisation that allows web-based contributions and management. Combined with the Translate Toolkit it allows Mozilla products t…

Privacy on the web is not well controlled by the user. There are cases where the user has explicit and desired relationships with sites (or, in the broade…

This article addresses the use of relative "em" and "ex" units in CSS, which can potentially cause rendering problems due to pixel rounding errors . Read …

The correct title of this article is about:config . It appears incorrectly here due to technical limitations in the wiki software. about:config is a featu…

The Thunderbird Council is the elected governing body for the Thunderbird Project , including the code modules that develop the code in Thunderbird produc…

Mozilla uses GeckoView to power Firefox for Android , Firefox Reality , Firefox Focus , and other Android apps. GeckoView serves a similar purpose to Andr…

Mozilla Thunderbird 2.0.0.4 was released on Thursday 14th June. This update to the Mozilla Corporation's mail client includes bug fixes but no new feature…

(5/1/2018) The Electrolysis Project is officially complete. Mozilla continues to work on scaling the Gecko process model through newer projects and work, …

The open, global internet is the most powerful communication and collaboration resource we have ever seen. It embodies some of our deepest hopes for human…

⚡ Warning: The content of this page is obsolete and kept for archiving purposes of past processes. These pages on wiki.mozilla.org are about XULRunner dev…

NOTE: this page has been made obsolete and is no longer maintained. For up to date information on Mozilla's strategy, AI work, OKRs and more, please visit…

Please note: the API is called "WebExtensions" because it can be found in search engines; "Web Extensions" (with a space) does not yield relevant results.…

The Password Manager can be used to automatically fill in the username/password needed to access web sites and log into mail servers. However, it stores t…

The EFF published an excellent study in May, detailing some of the various methods of fingerprinting a browser. See http://www.eff.org/deeplinks/2010/05/e…

Get all the speed and tools with none of the invasions of privacy. Firefox Browser collects so little data about you, we don’t even require your email add…

In Bugzilla, almost every patch that is submitted goes through a process of review, where it is looked at by an experienced Bugzilla developer to make sur…

Firefox is a key expression of Mozilla's mission and manifesto ; it represents our vision of a people-centric web experience, as well as a platform and to…

A protocol is a method that is used to send, receive, and handle information over a connection. Common protocols viewed from the browser include http , ht…

To get more information or talk to a human, or just to introduce yourself, see Thunderbird Communication Channels , especially the IRC channel. Again, we …

SVG Fonts address some use-cases which cannot be addressed using current OpenType-based solutions. For example: Editable text where the glyphs display a "…

This article describes how to prevent specific settings from being modified from inside Firefox, Thunderbird, or SeaMonkey. This is commonly known as lock…

By default Thunderbird and Seamonkey display the time only (without the date) for messages with today's date. For messages older than this, they display b…

Determine which root certificates should be included in Mozilla software products, which trust bits should be set on them, and which of them should be ena…

Whether you're technical or not at all, there's a contribution opportunity for you. It's easy to get started, and your efforts help to make Firefox better!

Get all the speed and tools with none of the invasions of privacy. Firefox Browser collects so little data about you, we don’t even require your email add…

Some websites require the use of the Windows Media Player (WMP) plugin for certain content such as embedded audio and video. This article describes how to…

The font-palette CSS property allows specifying one of the many palettes contained in a font that a user agent should use for the font. Users can also ov…

Do not automatically fill sign-in forms with known usernames and passwords; instead, act as though there are multiple usernames/password pairs remembered …

The installation directory is the directory where a Mozilla application stores its program files. It is usually a directory on your own computer. This app…

If you want a bug that is related to memory usage to be triaged in a MemShrink meeting, add "[MemShrink]" to the bug whiteboard. After prioritization, thi…

This schedule is based on the current RapidRelease plan. Future dates may change if the process changes. Code is not always released to users on the same …

This article is in parts, or in its entirety, outdated. Hence, the information presented on this page may be incorrect, and should be treated with due cau…

Firefox stores a user's personal information such as bookmarks, extensions, and user preferences in a unique profile . The first time you start Firefox, i…

URLs of the form /r/<id>/diff/[<revision>/] redirect to the associated commit in the review-repo archive . Note that, at the moment, all revisions of a gi…

This will make us the second/third browser to ship this, enabling more web developers to use it. That is, this helps with web compatibility and moves the …

A map of the skills and competencies people need to read, write and participate effectively on the web. Important note: Mozilla's Web Literacy Map was co-…

If you plan on presenting, please join the Zoom video chat 20 minutes prior to the start of the meeting and announce to the A/V Technicians that you will…

What is in this minimum policy? Is this automatic? If it is, can the author override it? How does this work with resources on CDNs and other domains? Is t…

In a market where changes constantly happen, 5 months is a long time for a feature to wait to be in an official build. I think this is going to push more…

First Look at Firefox-Based Netscape The Netscape Browser prototype is based on Mozilla Firefox 0.9.3. Netscape are very careful to use the term 'prototy…

This page discusses incidents, incident reporting, remediation, and communication. It gives guidance to CAs as to how Mozilla expects them to react to rep…

This document describes the minimum set of policy requirements that a party must satisfy to be considered as a potential partner for Mozilla’s Trusted Rec…

HTTP is the application-layer protocol with which most web pages are transferred. As part of HTTP, requests can include a "Referer" (sic) header that tell…

GNU/Linux Firefox uses the GTK setting to determine whether Emacs-like/Readline-like keybindings are active in text fields. There are two different metho…

This preference controls whether to use a pop-up alert or an error page for sites that can't be loaded because of a network problem. Possible values and t…

Give a man a fish, and he eats for a day. Teach a man to fish , and he eats for a lifetime. I like poetry, long walks on the beach and poking dead thing…

Think for yourself. Otherwise you have to believe what other people tell you. A society based on individualism is an oxymoron. || Freedom is at first th…

It is very common for IMAP users, especially those migrating from other clients, to delete their messages by "Mark it as deleted" instead of "Move it to …

Add your name and accomplishments under the appropriate month (please be specific). We choose an outstanding contributor ( Friend of Add-ons ) about once …

Contents Goals The problem is that right now our end to end time from checkin to all tests done is around 6-8 hours. That's wasting a lot of developer ti…

i ve been getting http://www.superfish .com blank page opening up on my firefox 3.6.8 lately , which is slowing down and blocking my access to other pages…

Since I installed 0.9 I have been having problems with the following: I have an email (Thunderbird 0.6) that has an ASP link to an order I made at compu…

<u><b>--== UPDATE / WORKAROUND FOR WINDOWS 95/98/ME/2000/XP ==--</b></u> This is now a known bug in bugtraq. It appears that Firefox 0.9 doesn't registe…

Seriosuly who reads to the bottom of this page anyway hoping to find something for their PPC machine ? Will anyone ever realize there are PPC releases ava…

SVG: Scalable Vector Graphics As such, it's a text-based, open Web standard for describing images that can be rendered cleanly at any size and are design…

In this article In this article Web APIs When writing code for the Web, there are a large number of Web APIs available. Below is a list of all the APIs a…

I discovered this 'feature' of Thunderbird when I had a client ask me to migrate him from Thunderbird to Outlook 2003 (keep reading and keep your politica…

In this article HTML: HyperText Markup Language HTML (HyperText Markup Language) is the most basic building block of the Web. It defines the meaning and …

When local HTML files (e.g., those located on your hard drive) are loaded into the browser, the scripts and links within have restrictions on what they ca…

Browse to the folder containing the bookmarks HTML file, select the file you wish to import and click "open". The imported bookmarks will be added to your…

In this article In this article Event reference Events are fired to notify code of "interesting changes" that may affect code execution. These can arise …

If you don't want to get a Github account, you can still clone the repository, but you won't be able to push upstream or issue pull requests: git clone h…

In this article WebAssembly WebAssembly is a new type of code that can be run in modern web browsers — it is a low-level assembly-like language with a co…

After upgrading to 3.6b4, i can't use my corporate proxy server anymore. It requires ntlm authentication and firefox does not seem to handle it correctly…

The FSA Executive Board is a dedicated collection of Mozilla Reps and passionate community volunteers who serve as leaders in the Student Ambassador progr…

CSP is designed to be fully backward compatible (except CSP version 2 where there are some explicitly-mentioned inconsistencies in backward compatibility;…

Web app manifests are deployed in your HTML pages using a <link> element in the <head> of a document: html <linkrel="manifest"href="manifest.json"/> The …

Cross-Origin Resource Sharing ( CORS ) is an HTTP -header based mechanism that allows a server to indicate any origins (domain, scheme, or port) other tha…

I'm on a Windows 7 (64-bit) desktop. Since upgrading to Firefox 6, I've noticed that Firefox will sometimes stop loading all web pages. I am able to cons…

This section is dedicated to the JavaScript language itself, and not the parts that are specific to Web pages or other host environments. For information…

By default, JavaScript is not allowed to read or set your clipboard data for security and privacy reasons. This is because websites scripts can erase and …

Asynchronously loads a page from the session history, identified by its relative location to the current page, for example -1 for the previous page or 1 f…

This page contains information about the community and how to reach out. Warning References below this point are part of the deprecated documentation and …

In this article WebGL: 2D and 3D graphics for the web WebGL (Web Graphics Library) is a JavaScript API for rendering high-performance interactive 3D and …

In this article Browser extensions Extensions, or add-ons, can modify and enhance the capability of a browser. Extensions for Firefox are built using the…

In this article Performance The Performance interface provides access to performance-related information for the current page. An object of this type can…

I am deeply honored and humbled by the CEO role. I’m also grateful for the messages of support. At the same time, I know there are concerns about my commi…

This article explains how to open multiple instances of your Mozilla application at the same time, using different profiles. It was written for Firefox bu…

Programming languages all have built-in data structures, but these often differ from one language to another. This article attempts to list the built-in d…

The same-origin policy is a critical security mechanism that restricts how a document or script loaded by one origin can interact with a resource from ano…

This morning, Adobe announced its roadmap to stop supporting Flash at the end of 2020. Working with Adobe and other browser vendors, Mozilla has prepared …

Subresource Integrity (SRI) is a security feature that enables browsers to verify that resources they fetch (for example, from a CDN ) are delivered witho…

Nearly all objects in JavaScript are instances of Object ; a typical object inherits properties (including methods) from Object.prototype , although these…

A Promise is a proxy for a value not necessarily known when the promise is created. It allows you to associate handlers with an asynchronous action's even…

MozCamp Contents What Is MozCamp? MozCamps are a critical part of our Grow Mozilla program, aiming to mentor and train core contributors to help us bring…

Functions created with the Function constructor do not create closures to their creation contexts; they always are created in the global scope. When runni…

Contents Background CSS can use a variety of units for specifying dimensions. These units are classified as either absolute or relative. Absolute units (…