Current web browsers are complex, have enormous trusted computing bases, and provide attackers with easy access to modern computer systems. In this talk we introduce the Illinois Browser Operating System (IBOS), a new operating system and a new browser that reduces the trusted computing base for web browsers. In our architecture we expose browser-level abstractions at the lowest software layer, enabling us to remove almost all traditional OS components and services from our trusted computing base by mapping browser abstractions to hardware abstractions directly. We show that this architecture is flexible enough to enable new browser security policies, can still support traditional applications, and adds little overhead to the overall browsing experience. I will also talk briefly about some of my groups recent work in defending against malicious hardware.