Spintronics (also known as magnetoelectronics) is an emerging technology which exploits the intrinsic spin of electrons and its associated magnetic moments, in addition to its fundamental electronic charges. Utilization of the electron’s spins has advantages such as low power consumption, and non-volatility over the conventional electronic devices. Magnetization dynamics in magnetic nanoscale devices has been intensively studied recently due to its potential in memories and logic devices. Two aspects of magnetization dynamics have been investigated in this book such as magnetic domain walls (particle-like objects) and spin waves (wave-like objects). The effect of current-induced spin transfer torque on the magnetization dynamics in which spin angular momentum from conduction electrons transfers to local magnetic moments has been explored. The main purpose of this study is in the utilization of the magnetization dynamics for device applications and each chapter of the book explores various characteristics of the magnetization dynamics.