Bagpipes are a class of musical instrument called aerophones, using enclosed reeds fed from a constant reservoir of air in the form of a bag. Though the Scottish Great Highland Bagpipe have the greatest international visibility, bagpipes have been played for centuries throughout large parts of Europe, the Caucasus, Turkey, around the Persian Gulf, and in Northern Africa. Bagpipes have been played in Scotland for more than six centuries.

The term bagpipe is equally correct in the singular or plural, although, pipers most commonly speak of them simply as "the pipes".

The instrument consists of a leather bag (or synthetic material) covered in decorative fabric, which the piper inflates via a blowstick. The bag serves as a reservoir/manifold and the air pressure is directed into four sounding locations: the chanter where the actual melody is emitted and three drones which are constantly playing a harmonious background. Two of the drones are the tenors and the longest is the bass. All three are tuned to the chanter by shortening or lengthening them along tuning slides. It is critical that the drones and chanter are tuned to each other, or the resulting sound is at best unpleasant. This reason alone explains why too many people believe the pipes nothing less than shrill and harsh noisemakers only because they've never heard properly tuned pipes played proficiently.

To play, the piper places the bag under his left arm and alternately inflates and squeezes air at a constant pressure through the chanter and drones. The art of piping is to produce an even tone and avoid any rise and fall in sound, or pauses between notes. It's a common misconception that the piper pumps the bag. Simultaneously, he must play memorized tunes, maintain rhythm, and walk or march about as needed. Few skilled pipers could be called klutzes.

The forced air passes through the drones and the chanter, and like any reed instrument causes them to vibrate and emit sound. The chanter is the only pipe that extends downward while the instrument is being played and has a slender, even delicate appearance. Ten holes drilled into the chanter allow creation of the notes. The chanter's reed is double-bladed, not unlike that of an oboe or bassoon. The drones do not each create a single tone, but generate complex harmonic blending into an acoustic sensation of resonance that reinforces the sound of the chanter. This background "humming" is what characterises the instrument and remains steady and continuous as the pipes are being played. Many assert that the humming is what attracts aficionados to the instrument. In the ancient development of the bagpipes, to accomodate the drones' harmonics, not all melody notes were selected. Some work extremely well, others with moderate success, and inclusion of other notes wasn't even debatable because they refused to harmonize with the drones. As a result the whole concept of sharps and flats is entirely unknown in bagpipe music. This also explains why pipers are often unable to play so many popular tunes. The total absence of certain notes, critical in Western music (classical, jazz, rock, etc) makes most of it impractical, if not impossible. Because the pressure must remain consistent, the volume is fixed at one level: LOUD. Its origin was as an instrument of war, to be heard above the din of battle. There is no method to quiet the pipes other than distance between them and the listener.

For our convenience, pipe music is written in standard musical notation without sharps or flats. It has been claimed that this unusual scale resembles the human voice, hence the old saying, "Let the pipes speak.", and the fascination so many people have with them. Children are particularly susceptible - ever read the story of The Pied Piper of Hamlin?

When listening to the bagpipes, one hears blips, chirps, and ripples throughout the music. These are intentional and known as grace notes. They consist of rapid short notes or elaborate combinations of short notes inserted between the notes of the melody and give the music its distinctiveness. And the various grace notes even have tongue-bending Gaelic names such as leumluath and taorluath.