Dots Per Inch (DPI)
Dots Per Inch (DPI) is the measurement of density of individual dots within a single inch and the space between those dots. This determines the resolution of images. The more dots per inch, the higher the resolution.
DPI is most frequently referred to when measuring resolution of digital imagery, and a common consideration for printers, digital cameras, imaging software (Adobe Photoshop), television and computer monitors. When referring to computer monitors resolution it is generally safe to translate DPI into pixels, as in Pixels Per Inch (PPI).
Computer monitors are most often set to 72 DPI (PPI) as a default standard. This means there are 72 dots across and 72 dots down, or 5,184 dots per square inch. Since most monitors have a native resolution of 72 DPI,they cannot display a 300 dpi image in actual size. Instead, when viewed at 100%, the image appears much larger than the print version because pixels on the screen take up more space than the dots on the paper.
NOTE:DPI is a measurement for a device, not an image. Scanners scan at the chosen DPI and printers print at selected DPI. By themselves the iamges on a computer does not have DPI.