In computer science and statistics, the Jaro–Winkler distance is a string metric measuring an edit distance between two sequences. It is a variant proposed in 1990 by of the Jaro distance metric (1989, ). The Jaro–Winkler distance uses a prefix scale which gives more favourable ratings to strings that match from the beginning for a set prefix length . Although often referred to as a distance metric, the Jaro–Winkler distance is not a metric in the mathematical sense of that term because it does not obey the triangle inequality.