Artificial selection occurs when man deliberately breed selected individuals to obtain offsprings with improved traits.
For instance, Japan has constantly developed improved rice cultivars by breeding rice plants with high grain yield (ie more rice grains per plant) with wild type rice plants with good disease resistance from 1950s to 1970s. This has greatly improved the rice grain yield and enabled Japan's rice self-sufficiency to approach 100%. The current objective has changed from high yield rice plants to rice plants with good eating quality.