Mutation refers to the process by which DNA sequence changes occur in an organism's genome. These changes can be caused by various factors such as errors during DNA replication, exposure to radiation or chemicals, or genetic recombination. Mutations can be beneficial, harmful, or neutral in their effects on an organism. They play a crucial role in evolution by providing genetic diversity upon which natural selection can act. Understanding mutations is important in various fields such as genetics, evolutionary biology, and cancer research.