Mutation = change in the genetic material in an organism

This occurs in non sex cells of sexually reproducing organisms and will not be passed on to the offspring.

The mutation may result in disease or death of the organism that it occurs in.

One consequence of a mutation is cancer, when the non sex cell undergoes uncontrolled mitotic cell division

If a mutation occurs in a sex cell or gamete, it may be passed on to its offspring.

Mutation as well as crossing over, and genetic recombination provides for variation in sexually reproducing individuals.