A flashcard or flash card (also known as an index card) is a card bearing information on both sides, which is intended to be used as an aid in memorization. Each flashcard bears a question on one side and an answer on the other. Flashcards are often used to memorize vocabulary, historical dates, formulas or any subject matter that can be learned via a question-and-answer format. Flashcards can be virtual (part of a flashcard software), or physical.