Gazelle was a research web browser project by Microsoft Research, first announced in early 2009. The central notion of the project was to apply operating system (OS) principles to browser construction. In particular, the browser had a secure kernel, modeled after an OS kernel, and various web sources run as separate "principals" above that, similar to user space processes in an OS. The goal of doing this was to prevent bad code from one web source to affect the rendering or processing of code from other web sources. Browser plugins are also managed as principals.