Stop motion (hyphenated stop-motion when used as an adjective) is an animation technique that physically manipulates an object so that it appears to move on its own. The object is moved in small increments between individually photographed frames, creating the illusion of movement when the series of frames is played as a continuous sequence.
The basic process of animation involves taking a photograph of your objects or characters, moving them slightly, and taking another photograph. When you play back the images consecutively, the objects or characters appear to move on their own
And the results are like this:
Stop motion animation is cool partly because it's insanely hard to make. You shoot one still frame, move the characters slightly, then shoot another then repeat thousands of times to make a little animation. While each individual frame may not be so tough, the overall effort is massive, and it shows. There's something about stop motion that just makes you say, "omg is that's real?!"