In QFT, renormalization is a way of mapping the behavior of a QFT at one distance scale onto its behavior at a different distance scale. Long story short, the

In QFT, renormalization is a way of mapping the behavior of a QFT at one distance scale onto its behavior at a different distance scale. Long story short, there's an equivalence between changing distance scales and changing the coupling constants in the theory. Once you get this mapping right, you discover the infinities present in the naive computations have vanished. (There is actually a quantity which has its normalization reset in this mapping, but that's actually the least interesting part of the story. It's somewhat odd that it's become the name for the whole mapping.)