Monitors / Displays Often DPI is advertized on products you buy. Such as monitors, phones, printers, scanners and inside software. It’s actually not so complicated to understand what it is in general. But it can be a little opaque sometimes especially when you talk printing, and image files. Then it’s easy to get a little confused. Actually DPI should be used when talking about prints, and PPI (Pixels Per Inch) should be used for displays.