Define/Explain: Multiple Allelism.

(N/A) Multiple allelism refers to the presence of more than two alleles for a single gene locus within a population. Although a single diploid individual can only carry a maximum of two alleles at a specific locus,the population as a whole exhibits multiple variations of that gene. $A$ classic example of this phenomenon is the $ABO$ blood group system in humans,where the gene $I$ exists in three allelic forms: $I^A$,$I^B$,and $i$.