Heegaard Floer homology gives invariants in lower dimensional topology and provides a powerful tool for studying classical topological problems.In particular,it determines the genus of a knot and the Thurston norm of threemanifolds,detects the fibredness of knot complements and three-manifolds.TheHeegaard Floer theory is equivalent to the gauge theoretic Seiberg-Witten theory.In this talk,we will briefly talk about the combinatorial description of Heegaard Floer homology, by the introduction of nice Heegaard diagrams. The talk includes the work of the author and collaborators and many others.