Some phenotypes are dominant, and some are recessive. We understand that this is because genes exist in individuals in pairs. So, we need to think in terms of the genes that control phenotypes. The A locus, one of the genes that controls coat colour. One of several alternative genes at the same locus.
Chromosomes exist in pairs in individual animals.
The Genotype is thus the set of Allele pairs on a set of paired chromosomes. It is the set of alleles on a single chromosome, or on all the single chromosomes passed from a parent to an offspring, or on a localized region of a single chromosome. Each individual receives an entire, single chromosome of each pair from both parents. Each individual passes an entire, single chromosome of each pair to each offspring produced. This process separating the paired chromosomes and passing only one of each pair to an offspring is called Meiosis.