Chrome applies the same kind of process isolation which we found in Operating System. Chrome by default launches each website you open in its own process. It keeps web apps and plugins in separate processes from the browser itself.
Browsers that put everything in one process face real challenges. If one web app causes a crash in the rendering engine, it will take the rest of the browser with it, including any other web apps that are open. Chrome avoids this by isolating each plugin and tab in separate processes.
Interestingly, Google Chrome has its own Task Manager which you can get to by right clicking on the browser's title bar(Or Press shift+Esc). This Task Manager lets you track resource usage for each web app and plug-in, rather than for the entire browser.
Read the Chome Introduction Comic for more details!