A mutation is a change in the genetic material (DNA or RNA) of an organism. This change can occur spontaneously and randomly, or it can be induced by external factors such as radiation or chemicals. Mutations can result in changes to the structure, function, or regulation of proteins, which may have various effects on the organism. Some mutations are beneficial, while others can be detrimental or even lethal. In some cases, mutations can lead to the development of new traits or characteristics that can be passed down through generations and contribute to evolution.