This paper examines the various aspects of access controls. First attempting to define access controls this paper will familiarize the reader with the concept and purpose of access controls. Next the four most common access control models are discussed as ways to simplify the process of implementing access controls. Mandatory Access Control (MAC), Discretionary Access Control (DAC), Role Based Access Control and Rule Based Access Control are all discussed and examined, including some of the most significant pros and cons for each methodology. Finally physical security is discussed and then tied into logical access control methods and how logical methods are an important aspect of all types of access controls.