Iteration
Loops potentially run code multiple times. Each time one goes from its top to its bottom we call that an "iteration" of the loop.
int x = 0;
while (x < 5) {
// On the 1st iteration x will be 0
// On the 2nd iteration x will be 1
// ...
// On the final iteration x will be 4
System.out.println(x);
x++
}
When the purpose of a loop is to run for every thing in some sequence of things, we say that the loop is "iterating over" those things.