The Picatinny rail ( or ), or Pic rail for short, also known as a MIL-STD-1913 rail or STANAG 2324 rail (canceled), is a military standard rail interface system that provides a mounting platform for firearm accessories. It was originally used for mounting of scopes atop the receivers of larger caliber rifles. Once established, its use expanded to also attaching other accessories, such as: iron sights, tactical lights, laser aiming modules, night vision devices, reflex sights, holographic sights, foregrips, bipods, slings and bayonets.
An updated version of the rail is adopted as an NATO standard as the STANAG 4694 NATO Accessory Rail.