Linear time-invariant system

A linear time-invariant (LTI) system is a type of system in engineering where the output depends directly on the input, following two key principles: linearity and time invariance. Linearity means if you double the input, the output doubles; if you add two inputs, the outputs add together. Time invariance means the system’s behavior doesn’t change over time—sending the same input today or tomorrow produces the same output. These properties make analyzing and predicting the system's behavior easier, as responses are consistent and proportional, which is useful in various signal processing and control applications.