Mutations that neither harm nor help an organism are called neutral mutations.

Here's why:

* Neutral mutations have no significant effect on an organism's fitness. They don't increase or decrease its chances of survival or reproduction.

* Harmful mutations decrease fitness, making an organism less likely to survive or reproduce.

* Beneficial mutations increase fitness, giving an organism an advantage.

Neutral mutations can occur in non-coding regions of DNA or in coding regions where the change in amino acid doesn't affect protein function. They can also occur in areas where the protein is not essential for survival.