PX

Px is most widely recognized as the abbreviation for pixel, the unit of measurement used to describe the resolution or size of digital images and screens. In digital imaging, graphics, and web design, px is used as a unit of length to specify dimensions such as width, height, margins, or font sizes. In CSS, 1 px is defined as a CSS pixel; on different devices, the number of actual device pixels per CSS pixel varies with the device pixel ratio, so a 100 px element may appear larger or smaller on different screens.

Origin and usage: The term comes from "pixel," which is short for "picture element." The abbreviation "px" is widely used across programming languages, design tools, and documentation to denote a pixel-related measurement.

Other uses: In military slang, PX (often capitalized) refers to Post Exchange, a retail facility on U.S. military installations. In some medical notes, Px has appeared as shorthand for prognosis, though practices vary and Rx remains the standard abbreviation for prescription. Outside of these contexts, Px may appear in various technical or branding names where it stands for different, context-specific terms.

Overall, px is most prominent in digital media discussions as a unit of length for images and layouts, with secondary meanings arising in distinct fields such as military retail and medical shorthand.

See also Pixel.