A single Firefox process. (credit: Roger)

With Firefox 50, Mozilla has rolled out the first major piece of its new multi-process architecture. Firefox 50 is also Firefox’s current stable release.

Edge, Internet Explorer, Chrome, and Safari all have a multiple process design that separates their rendering engine—the part of the browser that reads and interprets HTML, CSS, and JavaScript—from the browser frame. They do this for stability reasons (if the rendering process crashes, it doesn’t kill the entire browser) and security reasons (the rendering process can be run in a low-privilege sandbox, so exploitable flaws in the rendering engine are harder to take advantage of).

Moreover, these browsers can all create multiple rendering engine processes and use different processes for different tabs. This means that the scope of a crash is narrowed even further, typically to a single tab. Internet Explorer and Chrome both implemented this long ago, in 2009.