Head bob

Realistically depicted this should be extremely mild and only do up and down motion. Depending on the way one moves, head bob may be completely eliminated or emphasized. Side to side sway is likely only present in rather poorly articulated movement, such as running with swinging motion (flail arms more to the sides than back and forth).

This tag is generally only applicable to first person games.

Note that this is purely visual thing and is unlikely to have any effect on gameplay besides causing motion sickness on those with more sensitive stomach. Some might actually have this affect something, or represent accurately, thus allowing certain high precision actions to be pulled off more easily (or with more consideration of head position).