sight

A sight is a device used to assist aligning or aim weapons, surveying instruments, or other items by eye. Sights can be a simple set or system of markers that have to be aligned together as well as aligned with the target (referred to as an iron sights on firearms). They can also be optical devices that allow the user to see the image of an aligned aiming point in the same focus as the target. These include telescopic sights and reflector (or “reflex”) sights. There are also sights that project an aiming point onto the target itself, such as laser sights.
At its simplest, a sight is typically composed of two components, front and rear aiming pieces that have to be lined up. Sights such as this can be found on many types of devices including weapons, surveying and measuring instruments, and navigational tools.
On weapons, these sights are usually formed by rugged metal parts, giving these sights the name “iron sights”, a term relative to other weapon sights in that they are not optical…