Robert O'Callahan has a PhD in computer science at Carnegie Mellon and did academic research for a while at IBM Research, working on dynamic program analysis tools. At the same time he was contributing to Mozilla as a volunteer, until he switched gears to work full-time with Mozilla; Robert has been working on what became Firefox for over 15 years, mostly on layout and rendering in the browser engine and on related Web standards like CSS and DOM APIs. Lately he's been devoting about half of his time to rr.