How big is a pixel? It’s widely thought that a pixel is the smallest dot that screen hardware can physically display: One pixel is one pixel. That was safe to assume for over a quarter century because the pixel density of most of our screens was stuck between 72 and 120 pixels per inch (ppi) during that era, even while everything else about our computers got exponentially faster and bigger. But screens would finally make their move, and for designers that would change how a pixel is defined.

Want the whole story? Click the link below to read my article at CreativePro.com:
Rethinking the Pixel: It’s All Relative Now