stock's ratings - what the analysts could actually mean

I was talking to kishor today and he said he wanted to put some money into stocks... for some days I have been wondering what analysts meant when they said they have marked a company's stock as underweight or overweight.. the following article gives some of the basic meanings, but not the entire picture..

As it is said, all ratings are relative and are based on what someone has guessed or perceived the price of a stock to be in the future...

http://www.equitymaster.com/detail.asp?date=8/16/2004&story=6