Function pointers
The name of a function that you create is actually a pointer to that function. Applying the call operator (a pair of open and closed parenthesis) to a function pointer calls that function. (Built-in functions work differently; there is no function pointer.)
Function pointers are a distinct data type, and can be assigned to other variables or passed as parameters. The function can then be called through that function pointer variable.
Function pointers enable you to assign a particular function to a variable or property. The decision can be made up front and changed as needed. Then that function can be called as needed, without having to decide which function to call every time.