  I will present a new method for thinking about and for computing loop
integrals based on differential equations. All required information is obtained
by algebraic means and is encoded in a small set of simple quantities that I
will describe. I will present various applications, including results for all
planar master integrals that are needed for the computation of NNLO QCD
corrections to the production of two off-shell vector bosons in hadron
collisions.
