Also known as the pan pipe(s) or syrinx, the pan flutes are an ancient group of musical instruments based on the principle of the closed tube, consisting of multiple (usually 5 or more) pipes of gradually increasing length (and, at times, girth). The pan flute is played by blowing horizontally across an open end against the sharp inner edge of a pipe. Each pipe is tuned to a keynote, called the fundamental frequency. By overblowing, odd harmonics may also be produced.

The pan flute has long been popular as a folk instrument, and is considered the first mouth organ, ancestor of both the pipe organ and the harmonica.

The pan flute is named for its association with the rustic Greek god Pan.

The pipes of the pan flute are typically made from bamboo or giant reed (Arundo donax); other materials used include wood, plastic, and metal. The pipes are stopped at one end, at which the standing wave is reflected giving a note an octave lower than that produced by an open pipe of equal length.

In the traditional South American style, pipes are fine-tuned to correct pitch by placing small pebbles or dry corn kernels into the bottom of the pipes. Contemporary makers of curved Romanian-style panpipes use wax (commonly beeswax) to tune new instruments. Special tools are used to place or remove the wax. Corks and rubber stoppers are also used, and are easier to quickly tune pipes.