Speciation is the process by which new species arise from existing ones. This typically occurs when populations of a species become isolated from each other, leading to differences in their genetic makeup over time. Factors such as geographical barriers, environmental changes, or behavioral differences can contribute to this isolation. As these populations evolve separately, they may develop distinct traits and adaptations. Eventually, these changes can become significant enough that members of the two groups can no longer interbreed, resulting in the formation of new species. This process is a key mechanism in the theory of evolution, as described by Charles Darwin.