Vibes is the common abbreviation for the Vibraphone.  It is a percussive, but tuned, instrument, with metal bars arranged like a keyboard, but struck with hammers.  A resonating tube is hung under each bar, which amplifies the sound.  Thus far, it has considerable resemblance to the xylophone and marimba.  What distinguishes it is its vibrato effect  (a wavering of the pitch), which is generated by an electric motor which rapidly opens and closes the tops of the resonating tubes.

The vibraphone was invented about 1920, and it is mainly used in jazz ensembles, popular orchestras, and bands.