The trend of high pixel density screens that started with smartphones and tablets has spread to computer monitors. 4K computer screens have arrived over the last decade, and pixel density has become a key factor in product selection alongside screen size and resolution. Our theme is the transition to high pixel density screens, including the latest technology trends. There are two standards for 4K resolution, "DCI 4K" and "UHD 4K".

DPI (dots per inch) is the number of dots included in a 1-inch line for scanning or printing. For monitors and displays, DPI was dropped in favor of PPI (pixels per inch). While PPI is an accurate term for monitors and other displays, the two terms are often used interchangeably.

Given the changing relationship between screen resolution and the pixel density of a particular display, the question of what is my screen resolution is more difficult to answer than one might think, leading to the invention of the term device pixel ratio.

The number of device pixels that make up CSS pixels in one direction is the device pixel ratio (DPR). You can interpret it as the pixel width (or height) of the (physical) device that fits in one CSS pixel