In [[molecular biology]] ], '''SNP array''' is a type of [[DNA microarray]] which is used to detect [[Polymorphism (biology)|polymorphisms]] within a population. A [[single nucleotide polymorphism]] (SNP), a variation at a single site in [[DNA]], is the most frequent type of variation in the genome. Currently, there are around 85 million SNPs that have been identified in the [[human genome]].<ref>{{cite journal |doi=10.1093/nar/29.1.308 |pmid=11125122 |pmc=29783 |title=DbSNP: The NCBI database of genetic variation |journal=Nucleic Acids Research |volume=29 |issue=1 |pages=308–11 |year=2001 |last1=Sherry |first1=S. T. |last2=Ward |first2=M. H. |last3=Kholodov |first3=M |last4=Baker |first4=J |last5=Phan |first5=L |last6=Smigielski |first6=E. M. |last7=Sirotkin |first7=K }}</ref>
