Focus Priority
A setting that prevents the shutter from firing until the camera confirms focus has been achieved.
In depth
Focus priority guarantees no out-of-focus frames but costs missed moments, since the camera may refuse to fire at the peak of an action. It is the sensible default for portraits, product work and anything repeatable, and a liability in reportage where an imperfect frame beats no frame at all.
Examples in practice
With focus priority set, the shutter refuses to release as a subject passes behind a pillar, resuming the moment they reappear.