A genotype is the genetic makeup of an organism, representing the specific alleles inherited from its parents. It determines various traits, such as eye color or height, and is often denoted using letters, like AA, Aa, or aa, where each letter represents a different allele of a gene. Genotypes can be classified as homozygous, where both alleles are the same (e.g., AA or aa), or heterozygous, where the alleles are different (e.g., Aa). Understanding genotypes is essential in fields like genetics, agriculture, and medicine, as they influence how traits are expressed and inherited.