mutation

A mutation is a change in a cell's DNA — a tiny typo in the instruction manual that life copies and passes on. One letter of the genetic code gets swapped, dropped, or added, and that small edit can ripple out into a real difference.

Most mutations do nothing noticeable, or nothing at all — the code has built-in slack. A few are harmful, and once in a while one happens to be useful. Which it turns out to be depends entirely on the situation, not on the mutation itself.

Here's the part people miss: a mutation isn't "bad" by nature. It's just change. In fact, mutations are the raw material evolution works with — without these typos, there'd be no variety for nature to select from, and living things could never adapt.