DPI may refer to any of the following:
1. Short for dot per inch, DPI is a measurement of printer resolution indicating how many ink dots the printer can place in one square inch, the higher the DPI the sharper the image. Therefore, a printer that may have 600 DPI is a printer that can print 600 x 600 per square inch or 360,000 dots per inch. Because all printers print using a series of dots, printers with a low DPI may encounter jaggies. Resolution Enhancement and other edge enhancements help correct the appearance of jaggies with printers that support this technology.
Tip: When working with graphics only meant for a computer screen, 72 DPI is sufficient. Any graphics that you intend to print should have at least a 300 DPI.
2. DPI, or dots per inch, is also used to determine an image resolution.
Tip: When scanning an image that you intend to send over e-mail or only intend to have viewed electronically, scan the image as 72 DPI to keep the image size small.