SNPs are recognized by comparing aligned sequences of DNA. A single location along a pair of “matching” sequences, at which two nucleotides differ, constitute a SNP. In the above example, the swap of thymine (T) for adenine (A) is such a SNP.
SNPs are biological markers in the genome of humans and other life forms. SNP comparison—by using human genomes from distinct populations around the world—helps to understand genetic diversity of humans and, for example, regiospecific disease patterns and human adaption to different environments.
A recent article by Gary Styx illustrates the role of SNP in studying the historical path of human migration around the globe all the way to contemporary human diversity .
Keywords: bioinformatics, evolutionary anthropology, ancestry, DNA building blocks, diversity of DNA
References and more to explore
 An earlier SNP post on Latintos: http://golatintos.blogspot.com/2010/10/acronym-in-genomics-snp-for-single.html.
 Genetics Home Reference: What are single single nucleotide polymorphisms (SNPs)? [ghr.nlm.nih.gov/handbook/genomicresearch/snp].
 SNPedia: Single Nucleotide Polymorphism [snpedia.com/index.php/Single_Nucleotide_Polymorphism].
 National Human Genome Research Institute/Francis S. Collins: Single Nucleotide Polymorphisms (SNPs) [www.genome.gov/Glossary/index.cfm?id=185].
 Gary Styx: Traces of a Distant Past. Scientific American Winter 2013, 22 (1), 60-67.