A monotonic function is a type of function that consistently increases or decreases throughout its entire domain. If a function is monotonic increasing, it means that as the input values increase, the output values do not decrease. Conversely, a monotonic decreasing function means that as the input values increase, the output values do not increase. Monotonic functions are important in mathematics because they help in understanding the behavior of functions and their graphs. They are often used in calculus and analysis, particularly in the study of limits and continuity. Examples of monotonic functions include linear functions and exponential functions.