The harpejji is a unique stringed instrument invented in 2007 by Tim Meeks. It is designed to bridge the gap between the piano and the guitar. The instrument consists of a flat board with many strings tuned in whole steps. It is played by tapping the strings with the fingertips, similar to a piano, but it allows for techniques like string bending and vibrato, which are characteristic of the guitar. The harpejji uses a 'pure' isomorphic keyboard layout, meaning that a chord shape remains the same regardless of which key it is played in, making it very intuitive for music theory applications. It has been popularized by world-class musicians like Jacob Collier and Stevie Wonder. Despite being a modern invention, it is an purely acoustic-electric instrument, meaning the sound comes from real strings being struck, which are then amplified by pickups.