Moonpi where do you find that kind of information? When I went to school we didn't have fonts
I went to technical school half a day and learned to run printing presses, set type, operate commercial darkroom equipment, make plates for offset printing, and print stuff. Our final project was to research, write, typeset, and publish a paperback book of 50 pages or more.
Any desktop publishing site will explain proper use of display fonts. When all else fails, just try it both ways and stand back a few feet. The legibilty factor will become apparent immediately. There is a slideshow about typography here:
http://www.slideshare.net/markboulto...ter-typography