A karyotype is a photomicrograph of an individual's chromosomes arranged in a standard format showing the number, size, and shape of each chromosome type. Each chromosome is characterized by the length of its arms and the location of its centromere, which appears as an indentation or a lightly stained region. Staining methods may result in banding on the chromosomal arms (chromatids); chromosomes can then be identified according to their banding pattern. Karyotypes are used in low-resolution physical mapping to correlate chromosomal abnormalities with the characteristics of specific diseases.