an ounce is 28 grams. An ounce of good shit in the U.S. can go for between 200 and 500 dollars (usually). The ounce is further broken down into halfs, quarters and eigths. whenever you hear someone talk about fractions, it's of an ounce. Also, some people like to buy "dimebags", which arent a specific amount of weed but just what the dealer estimates to be worth 10 dollars. Obviously, dealer integrity varies so i like to know just how much pot I'm getting, to make sure im not getting ripped off. Most casual smokers i know buy eights, but buying more at one time will get you a better deal, so I usually buy an ounce a month and smoke about a quarter a week.