Levenshtein Distance

Levenshtein distance, also called edit distance, measures the minimum number of single-character edits (insertions, deletions, substitutions) needed to transform one string into another. Introduced by Vladimir Levenshtein in 1966, this metric is a true metric (satisfying all distance properties) and is fundamental in computational linguistics, spell checking, DNA sequence comparison, and record linkage. It ranges from 0 (identical strings) to the length of the longer string.