What is a natural trumpet?

A natural trumpet is a valveless brass instrument that produces sound by the vibration of player's lips against the mouthpiece. It has a cylindrical bore and a flared bell, and is typically made of brass or silver. The natural trumpet is capable of playing a limited number of notes, called the harmonic series, which are determined by the length of the instrument and the overblowing technique used by the player. The instrument has been used in music since ancient times, and is still widely used in classical music, jazz, and other genres.