The codon is the three letter word that spells amino acid. Each codon (three nitrogenous bases) in any order, will write for one of the 20 amino acids needed for life. For example, the codon A-A-A writes the amino acid lysine, whereas the codon G-A-A writes for the amino acid glutamine. Each of the amino acids has its own spelling words.
Each chromosome has roughly 10,000 codons! Now just imagine, if each nucleotide base measured 1 foot across, the codon would be 1 yard long. The whole chromosome would be 10,000 yards long or 1.89 miles long. So how many codons does it take to make a protein that can be used by our body? Well, it takes about 100 codons to as many as 1,000 codons to produce a protein that our body can use. Thus, 300 yards to a 1,000 yards of codons are needed to make a "gene". If each codon is read one at a time, you would have to walk down three football fields to get to the end of the message. In some cases you would have to walk down 10 football fields to get to the end of the message. In any case, a chromosome can have multiple genes along its length. Just imagine, 10,000 codons per chromosome times 46 chromosomes produces 460,000 codons. Wow, think of all those proteins. The primary function of DNA is to make proteins!