The classical Hall algebra is an algebra with a basis corresponding to isomorphism classes of finite abelian p-groups. This notion was implicitly suggested by Steinitz (1901). It was explicitly introduced by Philip Hall (1959). Ringel (1990) generalized the concept of Hall algebras to be compatible to more general categories, such as the category of representations of a quiver. We will talk a little bit about Hall algebras as described by Ringel , Schiffmann and Hubery. We will explicitly calculate the Hall algebra of some important quivers.