The remarkable structure and computationally explicit form of isogeny graphs
of elliptic curves over a finite field has made them an important tool for
computational number theorists and practitioners of elliptic curve
cryptography. This expository paper recounts the theory behind these graphs and
examines several recently developed algorithms that realize substantial (often
dramatic) performance gains by exploiting this theory.Comment: Invited ANTS X paper, minor edits, 18 page