Firefox vs the world

The vast majority of browsing is done on Chrome – so why do we still need Firefox? Nik Rawlinson finds out why we have multiple browser engines, and why it matters

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E very web browser is built around an “engine” – the core component that turns downloaded web code into the arrangement of text, images and interface elements displayed on your screen. This is commonly known as the browser engine or the rendering engine, as distinct from the various modules that take care of running the user interface, interacting with back-end elements, managing your passwords and so on.

You can think of this split like the parts of a car: the vehicle has a lot of components, such as the chassis, steering wheel, seats and seatbelts, but the engine is the part that makes it actually go. In browser terms, the engine isn’t just about how pages look – it determines how quickly and accurately they’re rendered, how they conform to web standards and how securely active content is handled.

In the early days of the web there were many different browsers, each using its own custom engine. Over time, the market has coalesced, and today there are only a handful of mainstream browsers; last year Cloudflare estimated that Google Chrome had a 68% share of the market, followed by Safari on 20%, Microsoft Edge on 5.7% and Firefox with 3.6%.

Together, those four add up to more than 97% of all browsing activity, and they do it using three different engines. By far the biggest is Blink, which is part of the open-source Chromium project developed by Google and used by both Chrome and Edge; the others are Apple’s WebKit (of which Blink was originally a fork) and Mozilla’s Gecko engine. Other engines exist and are used for some specific tasks, but you’re unlikely to encounter them in everyday web browsing.

But why do we need different engines at all – and does it really matter which one you use?

Browser wars warning

The main benefit of having multiple engines is diversity. If just one browser engine dominated the market, its owner could effectively define what “the web” was, by choosing which capabilities to prioritise and which to sideline.

This isn’t just a theoretical concern; as those with long memories will know, it’s happened before. The story begins back in 1995, when Microsoft introduced its brand-new Internet Explorer browser to compete with Netscape – arguably the first mass-market graphical web browser.