Factorization algebras are objects living on topological spaces that allow you to capture various kinds of algebraic data, from associative algebras to knot invariants to perturbative quantum field theories. In this talk, I will introduce the Costello/Gwilliam version of factorization algebras and discuss a result of theirs that shows how to obtain vertex algebras from factorization algebras over the complex plane. You don't need to know what a vertex algebra is for this talk!