CRE, which stands for Corewars Redcode Evolver, is an open-source program that automatically generates programs for the game Corewars by using Charles Darwin's theories on natural selection. When you start CRE, here's what happens: 1. A population of warriors is created by randomly selecting instructions. 2. Each warrior's fitness is tested by battling with other warriors in the population. 3. The fittest warriors reproduce and replace less fit warriors. 4. The previous two steps are repeated indefinitely.