Technical explanation
The carillon is a musical instrument, capable of producing a wide range of melodies and compositions. While electronic carillons exist, most are operated by live performers, called carillonneurs.
The carillon is operated by striking the pegs of a keyboard, which are connected to wires. Each wire pulls a clapper, which in turn strikes a stationary bell. It is extremely responsive, so that any tempo or dynamic is possible.
The keyboard is arranged like that of a piano, with a lower set of pegs corresponding to the white keys, and an upper set, arranged in groups of two and three, playing sharp or flat bells like the black keys.

Additionally, foot pedals are attached to the bottom-half of the keyboard, making complex performances possible for the experienced carillonneur.