A back cross is the cross of an F₁ hybrid with either of its parental genotypes (P₁ or P₂). A test cross specifically crosses an individual of unknown genotype with a homozygous recessive (aa) parent to determine whether the unknown is homozygous dominant (AA) or heterozygous (Aa). While the back cross includes the test cross as a special case, the general term for crossing F₁ with any parent is back cross. Test crosses are used to determine genotype; back crosses for breeding programme purposes.