Over-ear headphones come in all sorts of shapes and sizes but can primarily be broken down into just two types: open-back or closed-back. Whether a pair of over-ears is open or closed isn't always immediately apparent to the eye, but essentially it comes down to their structure and consequential effect on performance.
Closed-back is unarguably the most common type, with most wired and nearly all wireless models sporting a closed design, while open-back is the reserve only of wired over-ears (save for one notable exception: the Grado GW100x) and is typically more present in the higher-priced regions of that market.
