Cheat Sheet: What you need to know about Edge on Chromium

Microsoft’s news that it’s shifting its Edge web browser onto the Chromium engine has prompted discussion around a broad swathe of different web technologies. If you’ve found all the names and jargon confusing, you may find this reference of use.

We’ve put together a cheat sheet of key terms and technologies. It should help you understand the roles of the different projects and what’s changing within Edge. Phrases in italics in the definitions indicate a reference to another term within this cheat sheet.

Microsoft

• Edge – Starting simple, Edge is Microsoft’s modern web browser introduced with Windows 10. It’s built as a UWP app and is powered by the EdgeHTML browser engine. Last week, Microsoft confirmed that it will switch to the Chromium browser engine over the next year, and will gradually become available on more Windows versions and different operating system platforms. Edge currently uses the Chakra JavaScript engine, but this will be changed to V8 as a consequence of the move to Chromium.
• EdgeHTML – The proprietary Microsoft browser engine used by Microsoft Edge since its introduction with Windows 10 in 2015. The engine was split from Trident. Besides powering the Edge browser, EdgeHTML is also used to render various components of the Windows 10 interface, and supports Windows 10 UWP apps written with JavaScript and HTML. It is tightly bound to the Windows 10 system, and is not available for any other platform.
• Trident – Discontinued Microsoft browser engine used from Internet Explorer 4 until Internet Explorer 11. Responsible for much of Internet Explorer’s dominance during the early 2000s, but became outdated owing to poor compliance with web standards. Microsoft made efforts to improve the engine with additional features and standards support in later incarnations. The engine was also used to support JavaScript apps on Windows 8 and Windows Phone 8.
• UWP – Universal Windows Platform. A collective set of APIs and technologies which enable developers to create apps for Windows 10, Windows 10 Mobile and related modern Microsoft ecosystems. UWP is typically associated with the Microsoft/Windows Store, the most common distribution channel for these apps. Apps can be built for UWP using a wide variety of technologies, such as C++, C#/XAML and JavaScript/HTML. Options are also available to create UWP apps from existing classic Win32 Windows desktop apps, iOS apps, or PWAs.

Browsers

• Browser engine – Core, self-contained component of a web browser responsible for constructing and rendering webpages such that they are visible and interactive. Browser engines are usually opaque to the end user, who is typically unaware of their role in the browsing experience. The engine incorporates several sub-components, such as a layout engine and rendering engine, which implement different required functionalities for constructing webpages.
  Browser engines are usually, but not always, standalone components which can be implemented by multiple distinct web browsers – for example, the Chromium engine is currently used by Google Chrome, Opera, Vivaldi and many others. Each of these browsers has a unique interface and user-facing feature set, but relies on the Chromium engine to fetch, construct and render actual webpages.
• Blink – A popular and established open-source browser engine used by multiple web browser projects, including Chromium. Blink is broadly compliant with modern web standards and moves to implement emerging standards and recommendations in a timely manner, which has contributed to its popularity. It was forked from the WebKit engine.
• Chromium – An open-source web browser project originally developed by Google. Chromium is the foundation of many web browsers, most notably Google Chrome. It is powered by the Blink browser engine and uses V8 as its JavaScript engine. Chromium is available on all major desktop platforms, as well as Android. The project has drawn criticism for its close ties to Google; despite its open-source nature, Chromium development is led by Google, and the project includes default integration with Google services.

JavaScript

• JavaScript engine – A program that interprets and executes JavaScript code. Historically, most JavaScript engines have resided in web browsers, but in recent years JavaScript’s use outside of the browser has grown to include servers, command-line applications and mobile applications, necessitating evolution in engine development.
• Chakra – A JavaScript engine developed by Microsoft and used for Edge and UWP. It was forked from Microsoft’s older JScript engine. Initially a proprietary technology, Microsoft open-sourced the engine in 2015. Besides use in the Edge web browser, Chakra has also found popularity in other deployments, including embedded environments.
• V8 – An open-source JavaScript engine used primarily by the Chromium browser project, enabling the execution of JavaScript code inside web browsers. V8 is also used by many other JavaScript runtimes, including the Node.js server-side JavaScript environment, and the Electron desktop app framework.

Web technologies

• HTML – Hypertext Markup Language. HTML is the markup language used to create the structure and fundamental layout of webpages. Browser engines use HTML files to construct the webpage which is ultimately rendered to your display.
• JavaScript – A high-level interpreted programming language which is a core component of modern websites. JavaScript is essential to web apps and interactive pages as it provides developers with a way to interact with the webpage and the browser. JavaScript also has a wide range of use cases outside of web browsers, including in native apps (such as with Microsoft’s Windows 10 UWP platform), and on embedded devices.
• PWA – Progressive Web App. A set of development approaches, concepts and technologies which enable websites and web apps to behave like installed native apps on compatible devices.
  Features available vary by the platform on which the PWA is being used, but typically include the ability to “install” the website/web app in a manner akin to that of a native app, as well as support for service workers – a web technology which facilitates use of features such as offline operation, background sync and push notifications which are usually associated with native apps.
  PWAs are often mischaracterised by the tech media and non-developers as hybrid or hosted web apps. A pure PWA solely uses web standards to provide its functionality and is delivered from a website domain. It’s then up to individual platforms to implement the relevant web standards and provide a native-like experience.

This glossary provides a high-level overview of each of these technologies and terms; if you want to learn more, we encourage you to head to the websites of each featured project. Although these technologies may go unnoticed by users, they’re instrumental to the web and make it possible for us to consume webpages using our browsers.