Quizlet is a free online tool that allows students to create and study flashcards on various subjects. Students can choose from pre-made flashcard sets created by others or make their own flashcards. The tool makes studying vocabulary easy and enjoyable through interactive games like matching terms to definitions or pictures. Students can track their study time and share flashcards with friends. Teachers can use Quizlet to share classroom materials with students and have students create flashcards to teach vocabulary to each other.