Bordered Floer homology is an invariant for three-manifolds with parameterized boundary. It associates to a parameterized surface a differential graded algebra, to a three-manifold with boundary a module over that algebra. It can be used to recapture the invariant of a closed three-manifold, via the derived tensor product. I will describe this construction and some of its applications. This is joint work with Robert Lipshitz and Dylan Thurston.