Reading frame is a sequence of codons determined by nucleotides that are read in groups of three from a specific translation start codon, that is, it is a linear sequence of codons or triplets in a nucleic acid. It is one of three possible reading alternatives of a nucleotide sequence of a series of triplets, this means that, in a double-stranded DNA molecule, there are 6 possible directions in which reading frames can be opened; three in the forward direction and three in reverse.
