Procedures define functionality on a local level, however, it is smart for the programmer to want to know what is happening on the global level of their program. This is a hard thing to do.

There are common “shapes” of processes generated by procedures that correspond to the very valuable computational resources of time and space. This is known in a more modern sense as Big O notation, which deals with the time-complexity of a given algorithm - how long it will take to compute it. …