This document provides an overview of SDN (Software Defined Networking) and OpenFlow. It discusses the drawbacks of traditional networks including proprietary hardware and software that limits innovation. SDN aims to address these issues by separating the control plane and data plane, running the control plane on commodity servers, and using OpenFlow as a standard interface. OpenFlow allows the control plane to program the flow tables in switches using a secure channel. This provides centralized control and programming of the network. The document then covers OpenFlow in more detail, including its architecture, protocol messages, flow table processing, and potential use cases like load balancing.