J: Jams, Jellies (and Preserves and Conserves)

Photograph from iStockphoto.com
What's the difference between jelly and jam? Can you make a peanut butter and jam? Technically that's still PB&J, right? And what are preserves? Marmalades? And conserves? These days, when it's easy to just pick up a jar of Smucker's at the supermarket, why should we bother to try to make sense of these terms? Well, because it's National Peanut Butter and Jelly Day! And because homemade jams and jellies are easy to make and delicious to eat.