The traits of an organism are determined by sequences of DNA passed down from generation to generation.
One or more forms of a gene that produce different traits are called an allele.
One allele may produce a brown hair color, while another might produce blonde hair color.
Parents pass alleles to their offspring during reproduction.
The type of allele contained in DNA is called a genotype.
Bob possesses the genetic allele in his DNA for a widows peak hairline.
The type of physical characteristic that is a result of a certain allele is called a phenotype.
Bob's widows peak hairline is his phenotype.