Definition: A contraction of "picture" and "element", the pixel is literally an "image element". Rectangular in shape (or almost square) and small in size (between 0,18 mm and 0,66 mm side), is a colored and partial surface of an image. A so-called “pixelated” image designates a low resolution file, generating faint outlines and making it possible to distinguish the pixels. Note that this effect can be voluntary and applied for aesthetic or artistic purposes. We will speak of "pixel art".