A Mutation is defined as a change in the genetic material that is caused by an exchange, loss or addition of genetic letters. Some mutations arise as natural errors in DNA replication (or as a result of unknown chemical reactions); these are known as spontaneous mutations. Mutations can also be caused by agents in the environment; these are induced mutations.

The consequences of a mutation depend upon where in an individual they occur. Some mutations occur in regular body cells; these are somatic mutations. For example, someone who spends too much time sun tanning might experience a mutation in a skin cell. The consequences of such a mutation are felt only by the individual. The skin cell may develop some problem (such as cancer, perhaps) as a result of the mutation, but because the mutation occurred only in a skin cell, it would not be passed on to subsequent generations.

Some mutations occur in germline cells. These cells produce the gametes; therefore, they are gametic mutations. In most cases, such mutations wouldn't even be noticed by the individual. After all, the gametes don't play a prominent role in the day-to-day function of the individual. These mutations, in contrast to the somatic mutations, will be passed on to the next generation, because they occur in the cells that produce the next generation.