What is "bobbing" or "head bob"?

I was looking through Minecraft's menu options and I saw a toggle for "View Bobbing" and I didn't recognize what it meant. I've also heard of the phrase "Head bob" from this STALKER post, which sounds related but I'm not sure.

The Minecraft article describes the setting as:

"Chooses whether to show the bobbing when walking."

But that's very unclear. What is "bobbing" or "head bobbing" and how do they affect the games I play?

Solution 1:

Head bobbing in first person games is swaying the camera up and down as the character walks, to simulate the way a person's body moves up and down while taking steps. When especially prominent, it can cause motion sickness in players, so turning it off can reduce those effects.