Browser Engine

A browser engine, also known as a rendering engine or layout engine, is a central software component in a web browser. It translates HTML and CSS from plain text marked up with tags into the content you see on the screen — setting up the page layout, styling text, and placing images. The browser engine also handles navigation between pages using hyperlinks.

In addition to laying out the elements of a web page, the browser engine also creates a document object model (DOM) for each page, which organizes each page into standard elements like its title, body, and headers. The browser engine is also closely integrated with the browser's JavaScript engine, which executes a web page's JavaScript code. Updates to a browser engine can add support for new file formats, fix bugs, or support new features added to the HTML and CSS specifications.

Despite the wide variety of web browsers that are available, most use one of a handful of browser engines. Google Chrome uses the Blink browser engine; other web browsers based on the Chromium code base, like Microsoft Edge and the Brave browser, also use Blink. Safari on macOS, iOS, and iPadOS uses the WebKit engine, and Mozilla Firefox uses the Gecko browser engine. Other applications may include browser engines to display HTML content — for example, email clients that show HTML email use a browser engine to render messages, while apps built using a Chromium-based framework like Electron create their entire user interface using a browser engine.

NOTE: In early web browsers, rendering engines and browser engines were separate components, with the browser engine giving commands to the rendering engine. Modern web browsers integrate the two components so tightly that they are now considered the same.