A genotype is a scoring of the type of variant present at a given location (i.e., a locus) in the genome. It can be represented by symbols. For example, BB, Bb, bb could be used to represent a given variant in a gene. Genotypes can also be represented by the actual DNA sequence at a specific location, such as CC, CT, TT.
The genotype is the total set of genes present in each cell of an organism, i.e., all the genes that an individual has received from both parents. DNA sequencing and other methods can be used to determine the genotypes at millions of locations in a genome in a single experiment.
Some genotypes contribute to an individual’s observable traits, called the phenotype.