The circumferential scar on the penis that indicates where the scalpel, clamp, or other cutting or crushing device cut off the foreskin.

The circ scar may be a thin line or a wide band of actual scar tissue, and differs in pigmentation from the noticeable difference of the surrounding shaft and inner skin. The scar is often sexually sensitive, but can also be the site of painful surgical scar neuromas. The photos below show a wide range of scars:

Image Sources: www.halfclip.dyndns.info and www.circumstitions.com