The notation "f⁻¹(y)" represents the inverse function of a function "f" evaluated at "y." An inverse function essentially reverses the effect of the original function. If "f" takes an input "x" and produces an output "y," then "f⁻¹(y)" will take that output "y" and return the original input "x." For a function to have an inverse, it must be one-to-one, meaning each output corresponds to exactly one input. This property ensures that "f" can be reversed without ambiguity. Inverse functions are commonly used in various fields, including mathematics, science, and engineering.