The Unit Step Function, often denoted as u(t), is a mathematical function that is widely used in engineering and control theory. It is defined as zero for all negative values of time and one for all non-negative values. This function effectively "turns on" at time t = 0, making it useful for modeling systems that start operating at a specific moment. In signal processing, the Unit Step Function helps in analyzing and designing systems by simplifying complex signals into manageable components. It serves as a foundational building block for other functions, such as the Heaviside step function, and is essential in the study of Laplace transforms and differential equations.