Heegaard Floer homology is a package of invariants for 3 manifolds introduced by Ozsváth and Szabó, which is a symplectic alternative to more gauge theoretic invariants such as monopole Floer homology. A variation of this theory, called knot Floer homology, defines an invariant for knots in 3-manifolds. It was developed independently by Ozsváth and Szabó, and by Rasmussen. In this talk, we will outline the construction, some properties and applications of these invariants. If time permits, I will discuss my recent project to compute the knot Floer homology for a large class of satellite knots. This is joint work with Ian Zemke and Hugo Zhou.