Dots per inch

Dots per inch (DPI, or dpi) is a measure of spatial resolution for printing or image scanner dot density, in particular the number of individual dots (dot pitch) that can be placed in a line within the span of 1 inch (2.54 cm).

Description
Early laser printers were introduced at 300 DPI, though 600 DPI and higher have since become common. Commercial typesetters are typically 1200 DPI or higher.

Monitors do not have dots, but do have pixels; the closely related concept for monitors and video images is pixels per inch or PPI. Many resources, including the Android developer guide, use the terms DPI and PPI interchangeably.