Web browser engine

A web browser engine (sometimes called layout engine or rendering engine) is a program that renders marked up content (such as HTML, XML, image files, etc.) and formatting information (such as CSS, XSL, etc.).

A layout engine is a typical component of web browsers, email clients, e-book readers, on-line help systems or other applications that require the displaying (and editing) of web content. Engines may wait for all data to be received before rendering a page, or may begin rendering before all data are received. This can result in pages changing as more data is received, such as images being filled in or a flash of unstyled content if rendering begins before formatting information is received.

KDE's open-source KHTML engine is used in KDE's Konqueror web browser and was the basis for WebKit, the rendering engine in Apple's Safari and Google's Chrome web browsers, which is now the most widely used browser engine according to StatCounter. Current versions of Chromium/Chrome (except iOS version) and Opera are based on Blink, a fork of WebKit.

Gecko, the Mozilla project's open-source web browser engine, is used by a variety of products derived from the Mozilla code base, including the Firefox web browser, the Thunderbird e-mail client, and SeaMonkey internet suite.

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