Reflection: Iteration is repetition. When is this required and useful?
When is repetition useful? When we want to perform the same series of steps (process) on different data (inputs).
What is required for it?
Iteration is another method for abstraction: Carrying out a process repeatedly. Note the close relation between iteration and functions: Rather than constructing a loop, we could write a function and call this function repeatedly (with different inputs).
Any loop requires some criterion or condition that indicates wheter to continue and when to stop.