For a finite dimensional algebra Î of finite representation type and an additive generator M for mod Î, we investigate the properties of the Yoneda algebra Î = iâ„0 Ext i Î (M, M ). We show that Î is graded coherent and Gorenstein of self-injective dimension at most 1, and the graded singularity category D Z sg (Î) of Î is triangle equivalent to the derived category of the stable Auslander algebra of Î. These results remain valid for representation-infinite algebras. For this we introduce the Yoneda category Y of Î as the additive closure of the shifts of the Î-modules in the derived category D b (mod Î). We show that Y is coherent and Gorenstein of self-injective dimension at most 1, and the singularity category of Y is triangle equivalent to the derived category D b (mod(mod Î)) of the stable category mod Î. To give a triangle equivalence, we apply the theory of realization functors. We show that any algebraic triangulated category has an fcategory over itself by formulating the filtered derived category of a DG category, which assures the existence of a realization functor.