Bobasaur is correct. The pixel's he's referring to aren't the "classic" pixel, which is always square on computer screens under the standards they are set up (including your EGA example) under. Televisons, however, inclusive of HDTV, have a different standard that uses a rectangular pixel. In some situations, a computer creation will seem somewhat distorted on a televsion screen if the difference in pixel aspect isn't taken into account. Most video editing software adapts this as a default setting depending on the NTSC or PAL format.

thou and I, my friend, can, in the most flunkey world, make, each of us, one non-flunkey, one hero, if we like: that will be two heroes to begin with. (Carlyle)