A bass non-transposing instrument of the oboe family with a double reed.
Bassoons are typically made from (mountain) maple, and therefore more sensitive against moisture than oboes and clarinets. The air column (of 2,59 m) is folded in a bassoon, so the instrument has a total height of less than 1,50 m. The tonal range is similar to that of a cello, so typically bass clef and in higher range the tenor clef are used, sometimes even treble clef.
The contra-bassoon is notated the same way, but sounds an octave lower.
In classical era two bassoons were standard in an orchestra, in romantic era and later three bassoons and a contra-bassoon are not uncommon.