Ever heard of animations? Animations are more like videos being played on the screen when you play the game. They are no more than just images just being replaced by the next image, because the video data type in real is just a bunch of images being replaced by the next image very fastly that it seems like it is in motion.
In Unity, you can just select the images in stack, that you want to create an animation for, and then just add those images to an Animation object. Unity will create the object, and the animation for you. This is the beauty of Unity, that it lets you just drag and drop the images and the back-end coding will be handled by Unity itself.
Read this article, to learn more on which files to use, where to drop and what will be the result of the process.
http://unity3d.com/learn/tutorials/modules/beginner/animation[
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