A keyboard instrument is a musical instrument played using a musical keyboard. The most common of these is the piano. Other types of keyboard instruments include celestas, which are struct idiophones operated by a keyboard, carillons, which are musical instruments that are usually housed in bell towers or belfries of churches or other municipal buildings, and other non-acoustic instruments, such as various electronic organs, synthesizers, and keyboards designed to imitate the sound of other types of acoustic keyboard instruments or to create new musical sounds. Today, the term "keyboard" is mostly commonly used to refer to keyboard-style synthesizers. Under the fingers of a sensitive performer, the keyboard may also be used to control dynamics, phrasing, shading, articulation, and other elements of expression, depending on the design and inherent capabilities of the instrument.