What is meant by the redundancy of the genetic code?

The four letters (nucleotides) in our DNA code - ATGC - code for the thousands of different proteins that make up our metabolism and our human body. Proteins are made up of modular building blocks known as amino acids and there are 20 different amino acids in the human body. One amino acid is coded for by a string of three nucleotides known as a codon. There are 64 codons that code for 20 amino acids. The redundancy in the genetic code refers to the fact that there are more than one variation of codon that codes for the same amino acid. This is also known as the genetic code being degenerate.