Capo
Short for Capo d'Astro
If a guitar or banjo player wants to play in a different key without learning new scales, it's no problem.
Just place a "capo" at the desired fret, and you raise the pitch of all the strings at once, just as if you held the strings down with the finger of your third hand:
Here, the pitch is raised two frets, or one whole step. Now you can use the key of "C" fingering and you'll be playing in "D."
I can't think of a single instrument accessory that has been needlessly reinvented as many times as the capo! Here's a tiny assortment of new, old, cheap and expensive capos:
They all do the job, some a little better than others. . .