Endpin
End Pin
Endpin
At the "bottom" of a stringed instrument, where the sides meet at the end opposite to where the neck attaches, there's often a little button for attaching a strap. (Classical guitars don't have 'em, because classical players always sit to play.)
Here's a guitar endpin:
A traditional endpin fits into a tapered hole:
It needs to fit really tightly so it won't pull out! Sometimes they are glued in place, but that's not always the best idea. Glued endpins may make certain repairs a bit more difficult.
Some endpins are simple buttons attached by screws. Some endpins are combined with jacks to connect to an amplifier.
A violin has a small endpin to hold the tailpiece on. A string bass has a big ol' endpin with a central post that adjusts out to raise the instrument off the floor.