This tutorial article introduces the physics of spin transfer torques in magnetic devices, providing an elementary discussion of the mechanism and reviewing theoretical and experimental progress. The authors aim to make the content accessible to beginning graduate students. The article is part of a series of "Current Perspectives" articles on spin transfer torques published in the *Journal of Magnetism and Magnetic Materials*. It covers the history of the field, the importance of ferromagnetism, the origin of spin-polarized currents, and the impact of spin transfer torques on magnetic multilayer devices, tunnel junctions, and domain walls in magnetic nanowires. The article also discusses the potential commercial applications of spin transfer torques, such as in magnetic memory devices and high-frequency applications. The basics of ferromagnetism, including the origin of ferromagnetism and models of ferromagnetic materials, are explained, along with the concepts of micromagnetics and magnetic domains. The article concludes by discussing the dynamics of magnetic systems in the presence and absence of spin transfer torques, and how spin transfer torques can be incorporated into the equation of motion for magnetization dynamics.This tutorial article introduces the physics of spin transfer torques in magnetic devices, providing an elementary discussion of the mechanism and reviewing theoretical and experimental progress. The authors aim to make the content accessible to beginning graduate students. The article is part of a series of "Current Perspectives" articles on spin transfer torques published in the *Journal of Magnetism and Magnetic Materials*. It covers the history of the field, the importance of ferromagnetism, the origin of spin-polarized currents, and the impact of spin transfer torques on magnetic multilayer devices, tunnel junctions, and domain walls in magnetic nanowires. The article also discusses the potential commercial applications of spin transfer torques, such as in magnetic memory devices and high-frequency applications. The basics of ferromagnetism, including the origin of ferromagnetism and models of ferromagnetic materials, are explained, along with the concepts of micromagnetics and magnetic domains. The article concludes by discussing the dynamics of magnetic systems in the presence and absence of spin transfer torques, and how spin transfer torques can be incorporated into the equation of motion for magnetization dynamics.