In this video, I cover the basics of the action potential beginning with an explanation of membrane potential and how it sets the stage for the action potential. Then, I describe how an action potential is generated and how it ends. I cover the propagation of an action potential down the axon and the role myelin plays in this process. Finally, I discuss the absolute and relative refractory periods and what they mean for repeated action potential firing. Key points: 00:00 Introduction 0:17 Membrane potential 4:18 Action potential 7:20 Propagation down the axon and role of myelin 8:51 Absolute and relative refractory periods REFERENCES: Bean BP, Koester JD. 2021. Propagated Signaling: The Action Potential. In: Kandel ER, Koester JD, Mack SH, Siegelbaum SA, eds. Principles of Neural Science, 6th ed. New York: McGraw-Hill. Koester JD, Siegelbaum SA. 2021. Membrane Potential and the Passive Electrical Properties of the Neuron. In: Kandel ER, Koester JD, Mack SH, Siegelbaum SA, eds. Principles of Neural Science, 6th ed. New York: McGraw-Hill. Pinel JPJ. 2014. Biopsychology. 9th ed. New York: Pearson.