We have the allelat codes for the color green or we can have the allelat codes for the color yellow. So this particular trait, the color trait for seed color and Pea plants comes in two different alleles. So we have the green allele and we have the yellow allele. Now, sometimes we also have those traits that can have three or more different types of alleles for that particular trait. And in such a case, whenever we have a trait that contains three or more different types of alleles, that trait is said to have multiple alleles. And one particularly common example in which a trait has multiple alleles in humans is the human Abo blood group traits.