This lecture covers the group structure of elliptic curves, focusing on commutativity, inverses, and associativity. It explains how to define the inverse of a point on the curve and the concept of associativity in the context of elliptic curves. The lecture also discusses the isomorphism of elliptic curves to a specific form and explores the implications of this isomorphism. Additionally, it delves into the concept of compactification and its relation to the torus, showcasing the homeomorphism between elliptic curves and the torus.