Loops are magical things: they allow us to execute blocks of code for as often as we want.
One of them, the while loop, repeats while a boolean-type condition is true.
Boom! The code just runs and runs while the counter variable is less than 4. In this case, it runs 3 cycles, adding up to 4.
Psst: we've got to be sure that the condition becomes false at some point; otherwise it'd keep running and running. Or crash.
Not quite! We'll get to for loops soon enough though.