The features of Mozilla Firefox distinguish it from other web browsers such as Internet Explorer. It lacks many features found in other browsers, in an effort to combat interface bloat and to allow the browser to be shipped as a small, pared-down core easily customizable to meet individual users' needs. Instead of providing all features in the standard distribution, Firefox relies on the extension system to allow users to modify the browser according to their requirements.
Firefox supports tabbed browsing, which allows users to open multiple pages in the same window. This feature was carried over from the Mozilla Application Suite, which in turn had borrowed the feature from the popular MultiZilla extension for Mozilla. Firefox also permits the "homepage" to be a list of URLs delimited with vertical bars (|), which are automatically opened in separate tabs, rather than a single page. Firefox 2 supports more tabbed browsing features, including a "tab overflow" solution that keeps the user's tabs easily accessible when they don't fit horizontally, "session store" which lets the user keep the opened tabs across the restarts, the "undo close tab" feature, etc.
An integrated customizable download manager is also included. Downloads can be opened automatically depending on the file type, or saved directly to disk. By default, Firefox downloads all files to a user's desktop on Mac and Windows or to the user's home directory on Linux, but it can be configured to prompt for a specific download location. The download manager currently does not support cross-session resuming (stopping a download and resuming it after closing the browser). Another issue with the download manager is that it fails to close if small files or files already in the cache are downloaded. One advantage of the Firefox download manager is that the user can view the full source URL and destination path of the file being downloaded via the Properties box; Internet Explorer only shows the file name and source domain name
Powered by RSS or Atom feeds, "Live Bookmarks", another feature of Firefox, allow users to dynamically monitor changes to their favorite news sources. When this feature was first introduced in version 1.0 PR, there were a few worries that Firefox was beginning to include non-essential features and that it was beginning to bloat the browser much like the Mozilla Suite. However, these worries have largely abated. Instead of treating RSS-feeds as HTML pages like most news aggregators do, they are treated as bookmarks that are updated in real-time with a link to the appropriate source. Live bookmarks are updated automatically, however no browser option exists to prevent or control the automatic Live Bookmark updates.
add-ons in Firefox: extensions (for additional browser functionality), themes (modified browser appearance), and plugins (to view additional web content). Firefox add-ons may be obtained from the official Mozilla Add-ons web site or from other sources.
See also: Firefox Extension system and List of Firefox extensions Firefox users can add features and change functionality in Firefox by installing extensions. Extension functionality is varied; such as those enabling mouse gestures, those that block advertisements, and those that enhance tabbed browsing. Features that the Firefox developers believed would be used by a small number of its users have not been included in Firefox and left to be implemented as extensions. Many Mozilla Suite features, such as IRC chat (ChatZilla) and calendar have been recreated as Firefox extensions. Extensions are also often a testing ground for features that are eventually returned to the main codebase. For example, MultiZilla was an extension that provided tabbed browsing when Mozilla lacked that feature. While extensions provide a high level of customizability, PC World notes the difficulty a casual user would have in finding and installing extensions as compared to their features being available by default. Most extensions are not created or supported by Mozilla. As extensions have the same rights to the user's system as Firefox itself, it's possible to create malicious extensions. Mozilla provides a repository of extensions that have been reviewed by volunteers to not contain malware. Since extensions are mostly created by third parties, they do not necessarily go through the same level of testing as official Mozilla products, and they may have bugs or vulnerabilities
Firefox also supports a variety of themes/skins for changing its appearance. Themes are simply packages of CSS and image files. Many themes can be downloaded from the Mozilla Update web site. The change of default theme from Qute to Winstripe in Firefox 0.9 was subject to vocal debate. The Winstripe theme was created by heavily modifying Pinstripe, a theme designed with Mac OS X in mind. Prior to that, Firefox and its predecessors had used the Qute theme, designed by Arvid Axelsson. Due to licensing issues, the theme was prevented from being released under the Mozilla Public License. Axelsson was upset about being notified about the theme change only a few days before it took place, and posted the transcript of his dialogue with Ben Goodger, who had informed him of the change, on the MozillaZine forums, breaking the news before it was formally announced. Although many people criticized the new theme when it was rolled out, eventually the tension subsided. Axelsson continues to produce Qute privately. Axelsson still makes Mozilla Thunderbird's default theme
Firefox supports plugins based on Netscape Plugin Application Program Interface (NPAPI), i.e. Netscape-style plugins. As a side note, Opera and Internet Explorer 3.0 to 5.0 also support NPAPI. On June 30, 2004, the Mozilla Foundation, in partnership with Adobe, Apple, Macromedia, Opera, and Sun Microsystems, announced a series of changes to web browser plugins. The new API will allow web developers to offer richer web browsing experiences, helping to maintain innovation and standards. The new plugin technologies are expected to be implemented in the future versions of the Mozilla applications. Mozilla Firefox 1.5 and later versions include the Java Embedding plugin, which allow Mac OS X users to run Java applets with the latest 1.4 and 5.0 versions of Java (the default Java software shipped by Apple is not compatible with any browser, except its own Safari).
Beyond the use of Add-ons, Firefox additional customization features. * The position of the toolbars and interface are customizable * Hidden preferences in about:config which can be used to modify the behaviour of features and tweak performance. * User stylesheets to change the style of webpages and Firefox's UI.
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