Phonology is the study of sound patterns in language. It examines how sounds combine and change meaning. In 300 BC, Panini was the first to study phonology of Sanskrit. He created a grammar and list of phonemes with symbols still used today. Later, the French linguist Dufriche-Desgenettes first used the term "phoneme" and Baudouin defined it. Phonology tells us a language's sounds, how they combine into words, and which sounds contrast meaning. It also examines sound symbolism, onomatopoeia, assimilation, allusion, alliteration, stress, rhythm, and intonation.