DPI, PPI, Resolution - Know your screen

DPI (Dots Per Inch) originally referred to the resolution of printers, meaning the amount of dots per inch of paper that the printer was capable of achieving in order to form the texts or images that were printed. Of course the higher the DPI, the better the quality of the texts and images. To save ink however, a low DPI is often chosen (through the printer properties setting) for things such as draft copies or the normal paperwork.

Today DPI is also used to refer to the number of pixels that are present per inch of display screen (even though the more technically correct term is "PPI" or pixels per inch).

Just as with printers, the higher the DPI or PPI of your display screen, the better, clearer and more life-like the images will appear.  For example, a display screen with a resolution of 2048 x 1536 pixels (264 PPI pixel density) has approximately 3.1 million pixels on the screen (Apple iPad 4), while a screen with a resolution of 1024 x 768 pixels (132 PPI pixel density) will have about 786,000 pixels (Apple iPad 1).

I should warn you here that even though the more "pleasurable to the eye" would be the screen with the higher resolution (DPI/PPI), having more pixels also requires more battery power, more memory and more CPU processing power among other things, so when shopping for that smartphone or tablet do not just go for the higher resolution screen with the greater DPI, pay attention to the "size" of the battery, the amount of RAM/memory and the type of processor that is "under the hood" or you might find yourself with a great screen on a device that tests your patience to the boundaries of insanity.