The notation "g ∘ f" represents the composition of two functions, f and g. This means that you first apply the function f to an input value, and then take the result and apply the function g to it. In simpler terms, you are chaining the two functions together, where the output of f becomes the input for g. For example, if f takes a number and adds 2, and g takes a number and multiplies it by 3, then "g ∘ f" means you first add 2 to your number and then multiply the result by 3. This combined process allows for more complex transformations of input values.