Pixel Art is a form, a known type of art that involves taking a known picture, making an outline out of it, then going to make any edits as you see fit, or you can leave it as is.
Here, is one example of one (This is not done by me!)
This is one that's done of Sonic The Hedgehog. as you can see, there's an outline applied to the original picture, then is recolored and edited in order to make an almost duplicate of it.
After this post, I will try to post my own Pixel Art pictures.