A browser engine is the backbone of a web browser. Also known as a layout engine or rendering engine, a browser engine is what transforms HTML documents and other resources of a web page into a visual representation on the user's device.
Although they are often thought of as one, a browser engine works in coordination with a rendering engine and a JavaScript engine. Technically, the rendering engine serves to render web pages, while the browser engine handles communications between the browser's user interface and the rendering engine, and the JavaScript engine executes any JavaScript code that has been used in the page.
For the purposes of categorization here, however, we will consider these other engines to be part of the browser engine. The browser engine, the rendering engine, and the JavaScript engine work together to get the raw code that makes up the web page, and converts it into a form that is viewable within the user's browser.
Although several codes, scripts, and languages are included in the makeup of a web page, they can be broken down into three types: the code that represents the structure of the page, the code that provides style, and the code that acts as a script of actions for the browser to take. The browser engine combines the structure and style codes to display the web page on the screen, and to determine which parts of it are interactive.
When you are searching the web, you are not actually visiting websites. Rather, a copy of the pertinent data from the website is sent to your browser.
When a user enters the URL of a website that they wish to visit into the browser, or when they click on a hyperlink, the browser is given an address. At this address, there is another computer that, when asked, will send data back to the browser. Then, a lot of other things go on, which are beyond the scope of this guide but, in the end, the browser has the data in a format known as CSS, JavaScript, HTML, and other codes that describe the structure of the page.
A browser engine is the part of the browser that translates the HTML into something that can be displayed on the user's computer screen. A browser engine might be thought of as a translator, as it does the job of interpreting things.
It might also be compared to the engine of a car. Like a car, a web browser might look pretty but it can't run without an engine.
Although each of the many web browsers might offer differences in appearance, features, menus, and extensions, the browser engine has more to do with how a web page appears on your screen than the browser does. More often than not, any differences that you see in the way that a web page appears on your screen when it is viewed Chrome, Firefox, Safari, or another web browser, are due to the browser engine rather than the browser. These differences were far more dramatic a couple of decades ago than they are now, as vast improvements in standardization have improved the Internet experience for all of us.
Every web browser has, at its core, a layout engine. While there are far more browsers than there are layout engines, there are a variety of browser engines available to browser developers and, from time to time, a browser development team will change the engine behind its browser.
Layout engines are also known as browser engines, and they include, but are not necessarily limited to, Blink, EdgeHTML, Gecko, Goanna, KHTML, Presto, Servo, Tasman, Trident, and WebKit.
EdgeHTML was developed by Microsoft for its new Microsoft Edge browser, although it quickly switched to Blink. The Mozilla Foundation developed the Gecko engine, but Mozilla is also involved (along with Samsung) in Servo, which is at this point an experimental engine. Developed by Moonchild Productions, Goanna is a fork of Gecko. KHTML is a product of the KDE Project. The Presto browser engine was developed for use in Opera, but Opera transitioned to Blink, which is also used by Brave, Chrome, and Microsoft Edge. Tasman was used by Microsoft in its Macintosh version of Internet Explorer 5, but IE for Mac is no longer supported. Newer versions of Tasman are used in some other Microsoft products. Trident is another engine used in Microsoft Internet Explorer, some of which are still supported by Microsoft. EdgeHTML was a fork of Trident. WebKit was developed by Apple for its Safari browser, with continued development involving Adobe Systems, KDE, and Igalia, as well as Apple.
These, and any other browser engines, are the focus of this category.
Recommended Resources
A fork of the WebCore component of WebKit, as part of the Chromium project, Blink is used in the Google Chrome browser and several other projects. Announced in 2013, Blink remains similar to WebCore in many ways, although many of its features are implemented differently, allowing for greater flexibility for adding new features in future releases. Google has been a significant contributor to the project, which has also included Facebook, Microsoft, Opera, Adobe, IBM, Intel, and Samsung.
https://www.chromium.org/blink
Originally developed by Microsoft Corporation as Chakra, for use in its Microsoft Edge web browser, ChakraCore is a fork of the JScript engine used in Microsoft Internet Explorer. In 2015, core components of Chakra were open-sourced as ChakraCore and made available for downloading from GitHub under the terms of the MIT License. ChakraCore is largely the same as Chakra, but with platform-agnostic bindings. Build status, documentation, and other information is posted.
https://github.com/Microsoft/ChakraCore
Developed by Mozilla Foundation, Mozilla Corporation, and Adobe Systems, Gecko is a browser engine used in the Firefox browser, SeaMonkey, the Thunderbird email client, and in other applications. Free and open-source, it is available under the terms of the Mozilla Public License, and Mozilla supports its use on Android, Linux, macOS, and Windows platforms. Documentation for its use in various applications is put forth, and a community support forum is hosted.
https://developer.mozilla.org/en-US/docs/Mozilla/Gecko
Released in 2016, Goanna is the layout and rendering engine used in Unified XUL Platform (UXP) applications such as the Pale Moon web browser, the Basilisk browser, a fork of the K-Meleon browser, and the Interlink mail and news client. Goanna is a fork of Gecko, its development reflecting increasing Pale Moon’s divergence from Firefox. Among the differences between Goanna and Gecko is that the former is always run in single-process mode.
http://www.moonchildproductions.info/goanna.shtml
Used by the Konqueror web browser, KHTML is a browser engine developed by the KDE Project. Although development has been slow, it is still actively maintained, and several other engines have descended from KHTML. Distributed under the terms of the GNU Lesser General Public License, it is free software and hosted on GitHub, where its files, source, and documentation may be downloaded. Alternatives to KHTML, such as KDEWebKit, are also noted.
https://github.com/KDE/khtml
Also known as the Line Mode Browser, LMB, WWWLib, or just www, the Libwww Line Mode Browser is the second web browser ever created. Originally created by Tim Berners-Lee, Nicola Pellow, and others, the browser was designed to display text only, not images, and originally released in May of 1991. A development goal was for the browser to be platform-independent, and official ports have been established for several operating systems, and to support Telnet, hyperlinks, and Cyrillics.
https://www.w3.org/LineMode/
Developed by Mozilla Research, Samsung, and others, Servo is an experimental browser engine designed to take advantage of the memory safety properties and concurrency features of the Rust programming language. Although it is still under development, and a stable version has not yet been released, it can render Wikipedia and GitHub, and it passes the Acid2 test, featuring such innovations as a parallel layout algorithm and its own CSS3 and HTML5 parser.
https://servo.org/
Developed by Apple, Adobe Systems, KDE, Igalia, and others, WebKit is a browser engine used primarily in the Safari web browser, as well as Apple's iOS web browsers, the Blackberry Browser, the Wizen mobile OS, and Silk, the default browser for Kindle devices. Available primarily for macOS and Linux-type platforms, it is licensed under the terms of the GNU Less General Public License and the BSD License. As an open-source project, web developers are invited to contribute code and report bugs.
https://webkit.org/
