IUPAC notation is a commonly used system in which nucleobases are represented by the first letters of their chemical names: [G]uanine, [C]ytosine, [A]denine, and [T]hymine. This shorthand also includes eleven ambiguity symbols associated with every possible combination of the four DNA bases; these symbols were created to encode SNPs in related genes.
IUPAC notation is commonly used in alignments of DNA strings. See the figure below for a table detailing IUPAC notation.
