October 29, 2004 7:32 PM
In traditional typography, point size is defined as 1/72 of an
inch. Point size of a font is the distance from the top of the tallest
character to the bottom of the descenders in characters like j q
excluding accent marks. For a 10 point font, this would be 10/72
inch. Though in real life, the actual size of the font is not so
closely related to the point size.
A 10 point font is considered comfortable for long hours of continuous reading. Point sizes below that cause unnecessary eye strain.
Traditional video displays are 33% wider than their height. This gives an aspect ratio of 4:3 which has a history beginning at the time when Edison was making movies. Resolution settings like 640 by 480, 800 by 600, 1024 by 768 are all in the ratio 4:3. Resolution when calculated concerning printers is measured in dots per inch (DPI) whereas in video displays, it's measured in pixels per metrical unit (inches normally). If the horizontal resolution of a device is equal to the vertical resolution, it's said to have square pixels.
No matter which resolution is used by a video device, it should be able to display a readable 10 point font character. This can be done by taking into account the idea of a logical resolution size.
Source: "Programming Windows", Charles Petzold