WDFIDF is a method from search engine optimization (SEO) that combines two metrics: WDF ("Within Document Frequency") and IDF ("Inverse Document Frequency"). It is used for semantic text analysis and helps optimize content in a way that increases both topical relevance and search engine visibility. While WDF measures how often a term appears within a document, IDF reflects how rare the term is across a larger set of documents. A high WDFIDF score indicates that the term is both relevant and distinctive. This approach offers a deeper alternative to simple keyword density.