Reticle
The aiming pattern inside a scope: crosshairs, dots, or marked subtensions. Mil or MOA reticles let you hold over without dialing.
A simple duplex reticle (heavy outer, thin center cross) is fine for hunting at moderate distances. For precision rifle, a Christmas-tree or grid reticle with marked stadia at every mil (or MOA) is standard. That grid lets you read drop and wind correction right off the glass.
First focal plane (FFP) reticles scale with magnification, so subtensions stay accurate at any power. Second focal plane (SFP) reticles only read true at one magnification, usually maximum. That scaling is why FFP has become the standard for precision work.