McGrath has it right....boiling point. Further, you do not want the water to boil excessively, as this will gradually remove oxygen from the water and 'flatten' the taste.

   Tea is a bit more demanding than coffee, though both require a modicum of care to get the best result.

There are, of course, differences of opinions about details of steeping time, brands, types, flavors, what to add...etc...but basic preparation technique applies to all.