A guitar strap is a strip of material with an attachment mechanism on each end, made to hold a guitar via the shoulders at an adjustable length. Guitars have varying accommodations for attaching a strap. The most common are strap buttons, also called strap pins, which are flanged steel posts anchored to the guitar with screws. Two strap buttons come pre-attached to virtually all electric guitars, and many steel-string acoustic guitars. Strap buttons are sometimes replaced with "strap locks", which connect the guitar to the strap more securely.
The lower strap button is usually located at the bottom (bridge end) of the body. The upper strap button is usually located near or at the top (neck end) of the body: on the upper body curve, at the tip of the upper "horn" (on a double cutaway), or at the neck joint (heel). Some electrics, especially those with odd-shaped bodies, have one or both strap buttons on the back of the body. Some Steinberger electric guitars, owing to their minimalist and lightweight design, have both strap buttons at the bottom of the body. Rarely, on some acoustics, the upper strap button is located on the headstock. Some acoustic and classical guitars only have a single strap button at the bottom of the body—the other end must be tied onto the headstock, above the nut and below the machine heads.