1. To fit snugly into something, creating an audible snap when doing so. These pieces snap into slots near the base of the machine to stabilize it. The webcam snaps into a holster that I have mounted on top of my monitor.

2. To enter into some state or condition very suddenly or abruptly. I snapped into attention when my commanding officer entered the room. We all snapped into action the moment we heard the alarm.

3. To cause or force something to fit snugly into something else, creating an audible snap when doing so. In this usage, a noun or pronoun can be used between "snap" and "into." I just need to snap these wings into the fuselage and then my model airplane will be finished! The soldier snapped the magazine into the machine gun and began firing on enemy troops.

4. To cause someone enter into some state or condition very suddenly or abruptly. In this usage, a noun or pronoun can be used between "snap" and "into." The concussive impact had dulled my senses, but the searing pain in my shoulder snapped me back into focus. We all snapped into action the moment we heard the alarm.