A piano trio is written for a piano and two other instruments. Most of the time, these instruments are a violin and a cello. The term "piano trio" can refer to the group itself, or to the music written for such a group. In Classical times, a piano trio was usually written mostly for the piano, with the other instruments having much smaller roles. This was a consequence of the fact that the piano was quite weak. However, with modern instruments, all instruments can hold their own in an ensemble.
