Imagine printing the numbers 1 to 1000. You wouldn't write 1000 print lines. A loop runs the same block of code again and again. Python has two kinds: for: do something for each item in a sequence, or ...

A CPU keeps the values it is working on in a small set of fast registers. An instruction such as ADD R1, R2 reads two of them and writes one back, all in a single clock. The hardware that does this is ...