Mutation is a permanent change in the DNA sequence that constitutes a particular gene. The sequence differs from that of the vast majority of people, making it a genetic mutation and not a genetic variation. Mutations can affect a single DNA base pair or primarily affect multiple genetic codes. Evolution requires mutations because new alleles are created. However, unlike natural selection, mutations do not attempt to change to meet the needs of the organism. Mutations are random and while they can be beneficial, they are not always. Mutations do not always have a major effect on the host, but they are necessary for evolutionary change to continue to occur.