Keyboard instruments include the piano and the keyboard, which
is basically an electronic piano. Pianos are rarely included in a band but have
been used by a number of solo artists. An exception to this was the Beatles'
use of the piano in their song, 'Hey Jude". Electric keyboards are often
included in a band.
A Synthesizer is a computerized instrument that produces all
sorts of sounds. It is usually used to help create a mood, but sometimes the
sounds resemble other instruments. The master of the synthesizer was Rick
Wakeman, who had several hit concept albums in the 1970s.On a concept album the
songs work together to give the album a particular 'feel', rather than existing
as separate songs.