What do the letters in a genotype represent?

The letters in a genotype represent the genetic makeup of an organism. A genotype is the set of genes that an individual possesses, which can be represented using letters that denote different alleles. For example, in a simple genetic trait with two alleles, one might use "A" to represent a dominant allele and "a" for a recessive allele. The genotype determines the potential for certain traits to be expressed, though the expression of these traits also depends on environmental factors and interactions with other genes. Understanding the genotype is fundamental in genetics as it provides insight into hereditary information and how traits may be passed on to the next generation.