You can create full width layouts by using container-fluid. You can also nest a container inside of a container-fluid.
container-fluid is no longer valid in Bootstrap 3.0. Also, in previous versions of Bootstrap it still included a small right and left margin around the container. It just doesn't apply a fixed width to the container. If you want your carousel, background, etc... to bleed right to the browser edge, you need to work outside the container class.