In the full score of an orchestral composition, the families of instruments are arranged from top to bottom in the order of woodwinds,brass,percussion,strings.
These are the four main families of instruments. The string family includes the violin, the viola, the cello and the double (string) bass. The woodwinds include all tubes with an opening at one end and a mouthpiece at the other end (flute, clarinet,...) . Brass family includes bass, trombone, bass trombone, trumpet,...Timpani, snare drum, buss drum are some examples of instruments belonging to the percussion family.
