The genetic code is the set of rules by which information encoded in genetic material (DNA or mRNA sequences) is translated into proteins by living cells. The genetic code is highly similar across all Earth life forms and specifies how sequences of nucleotide bases in nucleic acids (DNA or RNA) correspond to amino acid sequences in proteins. The genetic code consists of three-letter "words" called codons formed from a sequence of three nucleotides, with some redundancy that allows some codons to specify the same amino acid.