DPI stands for ‘Dots per Inch’ “, more precisely the print-dots per inch and describes the dot density. So 300 dpi means a printer puts out 300 tiny dots of ink to fill in every inch of the print. In image reproduction, the dot density is a measure of the level of detail in a rasterized, visual reproduction and thus one of the quality aspects of the technical reproduction process.. This means that dpi is the technical printing resolution with which the print data is handled on a carrier medium. The dpi number depends on the specific printer.
In common parlance, there is no longer a distinction between dpi and ppi. In fact, even in the technical jargon of media designers, the terms are largely used synonymously. PPI describes the resolution in pixels in a digital image, whereas dpi describes the number of (print-)dots in a printed image.