  In 1912 Brouwer published his translation theorem, which implies, for
example, that an orientation preserving homeomorphism of the plane having a
periodic point also has a fixed point. This theorem has given rise to a number
of developments, leading among other things to Le Calvez's proof of the
existence of a Brouwer foliation for surface homeomorphisms homotopic to
identity. Recently, Le Calvez and Tal used this foliation to construct a
forcing theory intrinsically topological which, like Brouwer's theorem, allows
to deduce the existence of new orbits from certain dynamic properties of
homeomorphism. The expos{\'e} will describe the general principles of this
theory, as well as some of its many applications.
