Inspired by the recent developments in differential geometry and calculus of variations, there have been several approaches to identifying a suitable notion of local (Ricci) curvature on non-smooth spaces, such as graphs and Markov chains. I will describe some of these approaches and review a few recent developments in this topic on discrete curvature. Some of the consequences include a tight Cheeger inequality in abelian Cayley graphs, and diameter bounds on the spectral gap of the graph Laplacian. Several open questions remain.