I will describe a unified approach for constructing SRB measures which is pure geometrical and does not use any symbolic model of the system. This approach originated in the work of Sinai. I will first outline a construction of SRB measures in the classical case of uniformly hyperbolic attractors and then consider the most general case of non-uniformly hyperbolic chaotic attractors. This is a joint work with Vaughn Climenhaga and Dima Dolgopyat.