Abstract: The primary goal of this talk is to review some facts about reductive groups (i.e. section 5.3 of Whitehouse's notes), we will start with the definitions of reductive algebraic groups,  algebraic torus and F-anisotropic groups, we will mainly discuss the theorems on conditions for G to be compact and to have finite volume. If time permits, I may also try to some part of section 5.3, which is on the comparison of trace formulas.