Semisimplification is an operation on tensor categories which has seen increased usage in representation theory in the last decade.  I will begin by describing this operation, with examples, and then focus on its application to modular representations of reductive algebraic groups.  Quite a bit is now understood about the semisimplification of the category of tilting modules, which I will review.   Then I will discuss recent work in which we study semisimplification on arbitrary modules.  In a happy surprise, we obtain a highly explicit functor which has connections to the Finkelberg-Mirkovic conjecture, the latter being a geometric description of the principal block in terms of perverse sheaves on the affine Grassmannian.  Joint work with Baine, Fell, Romanov, and Williamson.