TF-IDF

The product of the normalized term frequency TF and the Inverse Document Frequency IDF. Often used for Information Retrieval.

tfidf⁡(t,d,D):=tf⁡(t,d)⋅idf⁡(t,D)\operatorname{tfidf}(t, d, D):=\operatorname{tf}(t, d) \cdot \operatorname{idf}(t, D)