copied from the bagpipes page

The Northumbrian bagpipes are a bellows-blown pipe with the interesting feature that the end of the chanter is closed, meaning that it is possible to play silences. This combined with the unusually tight fingering (each note is played by lifting only one finger) means that much Northumbrian piping tends to be very staccato in style. The chanter has a number of keys, most commonly seven, but two-octave chromatic chanters are occasionally seen, which require over twenty keys, all played with the right hand thumb and left hand pinkie! Traditionally, the chanter is pitched in F, but the music is written in G. Nowadays, chanters are available anywhere from D to G, G being the most popular for playing ensemble. There are usually four drones on the Northumbrian pipes, usually tuned to the tonic or the fourth. Many include a tuning bead, allowing the player to alter the drone's pitch by a whole tone, for playing in different keys.