What does the TF-IDF metric from On Page SEO Checker show?

TF-IDF (Term Frequency-Inverse Document Frequency) is a numerical statistic that reflects how important a word is to a document in a collection or corpus. It increases proportionally to the number of times a word appears in the document but is offset by the frequency of the word in the corpus, which helps to adjust for the fact that some words appear more frequently in general. Therefore, it helps identify words that are unique and relevant to a specific document. The other options are incorrect because TF-IDF does not measure traffic, search engine perception of a keyword, keyword usage in a URL, or human perception of keywords.