Which instrument is the most commonly used in the world?

The most commonly used instrument in the world is the guitar. It is used in a wide variety of musical styles, from rock to blues to folk to classical. The guitar is a stringed instrument that is played by plucking or strumming the strings with the fingers or a pick. It is one of the most popular instruments in the world, with an estimated 1.2 billion guitars sold since its invention in the 19th century.