Dry Malt Extract. You can get it at your brew supply shop. It is basically a powdered form of the malt that you would extract from grain in a mash session. They do that work for you, and you get a bag of DME, as it is. There is also LME, which is liquid malt extract. This is basically the same, with a few minor differences, and by weight, is not as strong as DME, since it still has a noticeable water content.