  This thesis describes experimental work on the use of wavefront shaping to
steer light through strongly scattering materials. We find that scattering does
not irreversibly scramble the incident wave. By shaping the incident wavefront,
we make opaque objects focus light as sharply as aberration free lenses. We use
feedback from a target behind, or in, an opaque object to shape the incident
wave. This way, light is focused through, or inside, opaque objects for the
first time ever.
