A short tandem repeat (STR) is a repeated DNA sequence occurring in DNA. STRs can be used to identify unique human cells. A STR profile can be generated by amplifying multiple STR loci and can be used for comparison studies. As more genetic regions are analyzed, the likelihood of two unrelated individuals having the same number of repeated sequences decreases. Thus, STR profile interpretation is common in forensic investigations because an individual's unique combination of STRs is highly unlikely to be observed in two individuals.