The pipa is a four-stringed Chinese musical instrument belonging to the plucked category. It has a pear-shaped wooden body and can have anywhere from 12 to 31 frets. The name 'pi' (to strike forward) and 'pa' (to pluck backward) refers to the two most common finger-plucking techniques. Originally, the pipa was played horizontally with a large plectrum, but by the Tang Dynasty, it transitioned to being held vertically and played with the fingernails. Modern players often wear high-strength plastic or tortoiseshell finger-picks to produce a loud, clear sound that can cut through a large orchestra. The pipa is famous for its 'martial' style (wen), which is loud and percussive, and its 'civil' style (wu), which is delicate and expressive. Its range of expression allows it to depict everything from the sounds of a fierce battle to the quiet ripples of water.