Campanology is the study of bells. It encompasses the physical realities of bells how they are cast, tuned and sounded as well as the various methods devised to perform bell-ringing. It is common to collect together a set of tuned bells and treat the whole as one musical instrument. Such collections such as a Flemish carillon, a Russian zvon, or a British "ring of bells" used for change ringing have their own practices and challenges; and campanology is likewise the study of perfecting such instruments, composing music for them, and performing it. In this sense, however, the word "campanology" is most often used in reference to relatively large bells, often hung in a tower. It is not usually applied to assemblages of smaller bells, such as a glockenspiel, a collection of tubular bells, or an Indonesian gamelan.