Within a population and due to competition between individuals, the individuals with an advantage will survive to pass their genes on to the next generation. What is this idea called?

Natural selection is the process where individuals with advantageous traits survive and reproduce more successfully than others in a competitive environment. These beneficial traits are then passed to offspring, becoming more common in the population over generations. Adaptation is the outcome of this process, not the process itself. Darwin's theory is broader, encompassing natural selection as the key mechanism.