The genetic codon is triplet and at each position of the triplet there are four possibilities due to presence of four nucleotides in nucleic acids, thereby meaning there are (\(4 \times 4 \times 4)\) or 64 possible codons. Out of these 64 possible codons, three codons UAA, UAG, UGA are termination codons. They do not code for any amino acids but result in termination of protein chain. Thus, 61 codons code for 20 essential amino acids.