Alleles refer to the alternative form of a gene that may result in different forms of traits of the same character.
For example, T and t are the alleles of the gene responsible for controlling the height of a plant. T codes for the tallness of the plant whereas t codes for dwarfness of the plant.
Similarly, in human blood groups , , and i are three alleles of a gene responsible for the blood group.
The different forms a gene may have for a trait are called alleles. Blood type is an example of alleles. They determine the hereditary characteristics an offspring gains from their parents.