Features of Firefox - Web Technologies Support

Web Technologies Support

Firefox supports most basic Web standards including HTML, XML, XHTML, CSS (with extensions), JavaScript, DOM, MathML, SVG, XSLT and XPath. Firefox's standards support and growing popularity have been credited as one reason Internet Explorer 7 was to be released with improved standards support.

Since Web standards are often in contradiction with Internet Explorer's behavior, Firefox, like other browsers, has a quirks mode. This mode attempts to mimic Internet Explorer quirk modes, which equates to using obsolete rendering standards dating back to Internet Explorer 5, or alternately newer peculiarities introduced in IE 6 or 7. However, it is not completely compatible. Because of the differing rendering, PC World notes that a minority of pages do not work in Firefox, however Internet Explorer 7 quirk mode does not either.

CNET notes that Firefox does not support ActiveX controls by default, which can also cause webpages to be missing features or to not work at all in Firefox. Mozilla made the decision to not support ActiveX due to potential security vulnerabilities, its proprietary nature and its lack of cross-platform compatibility. There are methods of using ActiveX in Firefox such as via third party plugins but they do not work in all versions of Firefox or on all platforms.

Beginning on December 8, 2006, Firefox trunk nightly builds pass the Acid2 CSS standards compliance test, so all future releases of Firefox 3 will pass the test.

Firefox also implements a proprietary protocol from Google called "safebrowsing", which is not an open standard.