What is idf meaning?

The term IDF stands for "Inverse Document Frequency." It is a measure used in natural language processing and information retrieval to determine the overall importance of a particular word in a given document or corpus.

The IDF value of a word is calculated by taking the logarithm of the total number of documents in a corpus, divided by the number of documents in the corpus that contain that word. This value represents how frequently the word appears across the whole corpus, and how much importance should be assigned to it in the context of the document in question.

IDF is commonly used in conjunction with another term known as TF or "Term Frequency," to calculate what is known as TF-IDF. Together these values allow for more accurate and relevant search results in search engines and other data retrieval systems.