In biology, a mutation refers to a change in the DNA sequence of an organism's genome. Mutations can result from various factors, such as errors during DNA replication, exposure to radiation or chemicals, and viral infections. These changes can be classified as beneficial, harmful, or neutral, depending on their effects on the organism. Mutations play a vital role in evolution and genetic diversity, serving as a source of variation for natural selection. They can lead to new traits or adaptations, impacting populations over time.