Raster graphics (pixel)
A raster graphic – also called a pixel graphic or bitmap – consists of a grid of many individual coloured dots (pixels). The number of these dots is fixed. Photos are always raster graphics.
If a raster graphic is stretched beyond its actual size, the individual pixels become visible – the image looks blurry or stair-stepped. How large a pixel image can be printed therefore depends on its resolution (see ppi).
Pixel images are edited in programs such as Adobe Photoshop, GIMP or Affinity Photo; typical extensions are .jpg, .tif, .png and .psd. For logos and type, a vector graphic is the better choice.