Evolution is the change in the characteristics of biological populations over successive generations. The core mechanism involves genetic variation within a population coupled with environmental pressures, leading to the differential survival and reproduction of organisms. This process of natural selection favors traits that enhance an organism’s ability to survive and reproduce in a given environment, thereby increasing the frequency of advantageous alleles in the succeeding generations. Over vast stretches of time, these accumulating changes facilitate the adaptation of life forms to diverse ecological niches, ultimately leading to the branching of lineages and the diversification of life on Earth.