In use for stringed instruments such as guitar and mandolin since the 17th century, later also the ukulele, the capo is a common tool with which the strings in a certain fret can be simultaneously and constantly pressed onto the fretboard. This uniformly shortens the vibration of all strings, causing the tone of the strings to sound higher (chromatically tuned instruments: one note higher per fret) (pitch offset). In this way you can play in a different key without having to change the picking patterns. The capo thus acts like a movable nut. From capotasto („main fret“)¹⁾ or capo d'astro ( „main star“).