G-banding is one of the chromosome staining techniques that results in banding patterns on chromosomes. It uses the chemical dye, Giemsa, to create distinct chromosome-specific patterns called G-bands. It allows the identification of each chromosome, as well as its different regions, relative to its banding pattern.
The method for G-banding begins with subjecting the chromosome to a treatment involving trypsin (a proteolytic enzyme), and then staining it with Giemsa. This produces dark-stained bands at the regions with lower G-C content.