In this paper we will cover the basics on Address Resolution Protocol (ARP), Media Access Control (MAC) Addresses, Wireless (WiFi), and layer 2 communications. I hope to explain how a "Man in the Middle Attack" works. The common name for this is ARP poisoning, MAC poisoning, or Spoofing. Before we can get into how the poisoning works, we need to learn about how the OSI Model works and what happens at layer 2 of the OSI Model. To keep this basic we will only scratch the surface on the OSI model to get the idea of how protocols work and communicate with each other.  The OSI (Open Systems Interconnection) Model was developed by the International Standards Organization (ISO) in 1984 in an attempt to provide some standard to the way networking should work. It is a theoretical layered model in which the notion of networking is divided into several layers, each of which defines specific functions and/or features. However this model is only a general guideline for developing usable network interfaces and protocols. Sometimes it may become very difficult to distinguish between each layer as some vendors do not adhere to the model completely. Despite all this the OSI model has earned the honor of being "the model" upon which all good network protocols are based.