A SNP (pronounced "snip") is a small genetic change, or variation, that can occur within an organism's DNA sequence. The genetic code is specified by the four nucleotides: adenine, cytosine, thymine, and guanine. SNP variation occurs when a single nucleotide, such as adenine, replaces one of the other three nucleotides. Snps found within a coding sequence are of particular interest to researchers because they are more likely to alter the biological function of a protein. Because of the recent advances in technology, coupled with the unique ability of these genetic variations to facilitate gene identification, there has been a heightened activities of SNP discovery and detection.