Most home tea drinkers use boiling water for everything. That's how you end up with a bitter Darjeeling, a vegetal-tasting white, and a matcha that's lost its umami. Different teas want different water temperatures, and the gap between them is bigger than you'd think.
Black teas — Earl Grey, Yunnan, Lapsang — like water that's just stopped boiling, around 95–100°C / 203–212°F. The tannins want heat to extract properly.
First-flush Darjeeling is an exception inside the black category. It wants 85°C / 185°F — about a minute off boil. Hot water bullies the muscatel note out of it.
Green teas want 75–85°C / 167–185°F depending on style. Gunpowder green like Moroccan Mint can take the higher end; sencha and bancha want the lower.
White teas want 80°C / 176°F. They're the most delicate; boiling water turns them papery.
Matcha wants 70°C / 158°F. Boiling water destroys the umami — the cup ends up tasting like astringent grass instead of broth.
Herbals — chamomile, mint, verbena — actually want full boil. They're not 'tea' in the camellia-sinensis sense; they're infusions, and the heat helps extract.
If you don't have a variable-temperature kettle, use this trick: boil water, then wait. Two minutes off boil = ~85°C. Five minutes = ~75°C. It's not exact, but it's close enough.
