DPI stands for dots per inch. DPI is a measurement of printer resolution that defines how many dots of ink are placed on the page when the image is printed. DPI does not correspond directly with PPI because a printer may put down several dots to reproduce one pixel. This is because printers use a limited number of coloured inks to reproduce an image consisting of millions of colors. The higher a printer's DPI, the smoother your printed image will appear, provided you have a suitable amount of image resolution (ppi).
Today's photo-quality ink jet printers have DPI resolution in the thousands (1200 to 4800 dpi). They will give you acceptable quality photo prints of images with 140-200 ppi resolution, and high quality prints of images with 200-300 ppi resolution.
The term DPI is often used interchangeably with PPI, causing a lot of confusion, however, DPI refers to the resolution of the printing device, where PPI refers to the resolution of the image itself.
PPI stands for pixels per inch. PPI is a measurement of image resolution that defines the size an image will print. An image that is 1600 by 1200 pixels at 300ppi will print at a size of 5.3 by 4 inches. Or it could be printed at 180 ppi for a printed size of 8.89 by 6.67 inches. The higher the ppi value, the better quality print you will get--but only up to a point. 300ppi is generally considered the point of diminishing returns when it comes to ink jet printing of digital photos.
The term DPI is often used interchangeably with PPI, causing a lot of confusion, however, DPI refers to the resolution of a printing device.