Genotype is the genetic constitution of an organism. Phenotype is the expression of this genetic constitution and its interaction with the environment. A Punnett Square allows for phenotypic ratios to be worked out.
Dihybrid inheritance is the inheritance of 2 characters determined by 2 different genes located on different chromosomes. A dihybrid cross investigates the genotypic and phenotypic ratios of 2 alleles between the cross of 2 parents.
There are 2 types of linkage: autosomal linkage (on non-sex chromosomes) or sex-linkage (on sex-chromosomes).
Aytosomal linkage is where 2 or more genes are carried on the same autosome. Linkage would cause the phenotypic ratio to be completely different than expected. Within sex-linkage, the production from a specific gene is carried either by the X or Y chromosome.
Epistasis is where one gene masks the expression of another gene. Alleles will be recessive epistatic or dominant epistatic.