What is the difference between genotype and phenotype?

In genetics, traits such as eye colour, sex and skin colour are carried in genes. Taking eye colour as an example, you will have a gene located somewhere within a chromosome encoding for eye colour. This gene has different alleles; which are different forms of a gene, in this case the colour blue, green and brown for example. You inherit one allele from your mother and one from your father, and these make up your genotype. However, in simple mendelian genetics, some alleles are dominant over other alleles, so for example the allele coding for brown eyes is dominant over the allele coding for blue eyes. So, if you inherit both of these alleles from your parents, only one of them will determine your actual eye colour; in this case brown. This is the phenotype; the actual allele which shows up as the observable characteristic.