A string metric for measuring the difference between two strings defined as the minimum number of single-character edits (insertions, deletions or substitutions) required to change one string into the other. For example, the Levenshtein distance between “kitten” and “sitting” is 3, since the following three edits change one into the other, and there is no way to do it with fewer than three edits:

1. kitten → sitten (substitution of “s” for “k”)
2. sitten → sittin (substitution of “i” for “e”)
3. sittin → sitting (insertion of “g” at the end).