Each subroutine is called by name, performs its task , and returns to the calling procedure. Functions are quite similar in that they are called to perform a specific function. The difference is, when they return, they bring back a value.
Functions only have one job- to find a specific value.
Recall that we have used functions. It returns the leftmost letter of the string. It returns the integer value of the string. There is also a difference in how functions are called . Since they always return a value, you as the programmer, must do something with that value.