Variation is an intrinsic property of living entities. New genetic variants are generated as organisms reproduce and their frequencies in populations may change with time. This temporal change of the genetic structure of the population of an organism is the process of evolution. Genetic variations that alter gene activity or protein function can introduce different traits in an organism. If a trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation. Genetic variability is different from genetic diversity. Genetic variability measures how much the trait or the genotype will tend to vary. Genetic diversity measures the number of actual variations of species in a population. Genetic variation is the raw material of evolution. Without genetic variation, a population cannot evolve in response to changing environmental variables and, as a result, may face an increased risk of extinction. Genetic variation is the presence of differences in sequences of genes between individual organisms of a species. It enables natural selection, one of the primary forces driving the evolution of life. Genetic variation describes naturally occurring genetic differences among individuals of the same species. This variation permits flexibility and survival of a population in the face of changing environmental circumstances. Genetic variability refers to the tendency of individual genetic characteristics in a population to vary from one another. It may also refer to the potential of a genotype to change or deviate when exposed to environmental or genetic factors.