An increasing function is a type of mathematical function where, as the input value increases, the output value also increases. This means that for any two points on the function, if the first input is less than the second input, the output of the first input will be less than the output of the second input. In simpler terms, the graph of an increasing function moves upward as you move from left to right. There are different types of increasing functions, such as strictly increasing functions and non-decreasing functions. A strictly increasing function means that the output always increases when the input increases, while a non-decreasing function may stay the same for some input values. Examples of increasing functions include linear functions like y = mx + b where m > 0 and exponential functions like y = a^x where a > 1.