Iced Tea is tea served chilled, sometimes with ice in it (as distinct from tea which has gone cold). There are several brands of iced tea on the market.
It might be noted that, while in the rest of the world, "tea," unmodified, normally refers to hot tea, and if you wish to order iced tea in a restaurant, you must specifically ask for it, in the Southeastern United States, it refers to iced tea, and if you wish to order hot tea in a restaurant, you must specifically ask for it. In the area around Washington, D. C., the borderline between the two, if you ask for "tea" without specifying "hot" or "iced," you will frquently be asked whether you want hot or iced tea, and if you are not asked, you might be served either, depending on the waiter's native dialect. It is, therefore, always preferable, when in this area, to say "hot tea" or "iced tea," when ordering, as the case may be.