Positive selection is a process in evolutionary biology by which beneficial traits or genetic variations become more common in a population over time. This occurs when individuals with advantageous traits have a higher chance of surviving and reproducing, passing down those beneficial traits to their offspring. Positive selection can lead to the adaptation and evolution of organisms in response to changing environmental conditions or selective pressures. Researchers study positive selection to understand how and why certain traits evolve and to gain insights into the genetic basis of adaptation in different species.