The organ as we know it developed froma group of individual organs brought together into one place to be played by one person. Each of these organs as its own character and volume controlled from its own keyboard. This allows for the use of contrasting sounds; they can also be joined together to give a bigger sound. The sound is produced by wind/air being blown into a pipe. They come in two (2) main types: flue and reeds.
These come in three (3) groups: foundation, flutes and strings.
The main sound on the organ and does not resemble any other musical instrument.
Pure, clear toned, a sound close to the flutes of the orchestra or the recorder etc. Used in contrast to the foundations or for solos.
Luscious, sensual, bright and warm sound can be made imitate orchestral string
Sound made by vibrating metal reed, can be a quiet stop (oboe) up to very-very loud (Fanfare Trompette) for solos or made to blend with the foundations (Cornopean)