WebKit is a rendering engine which is one of the major components of a web browser. Chrome/Chromium was released in 2008 using a modified version of WebKit as its rendering engine. Eventually in 2013 they created a fork of WebKit called Blink, which is the current rendering engine for Chrome/Chromium.
In more history, WebKit is a fork of KHTML. That’s the reason why WebKit itself is open source.
Apparently there hasn’t been active maintenance since 2016 though and it’s officially dead since this year. RIP
Remember Konqueror? That’s KDE’s web browser, which still uses KHTML. I should try it out again and see how it’s held up.
I’m not sure, but didn’t Konqueror switch to qtwebkit at some point? Or was that a different qt-based browser?