The appropriate water temperature varies based on the tea. Smooth teas prefer lower temperatures, whereas robust teas prefer higher temps. White tea, for example, requires water that is 160°F. Green tea is 150-180 degrees.
Oolong is finest at 190°. Black tea has a temperature range of 180-212 degrees. Finally, herbal teas are approximately 212°F. Many electric kettles may be pre-programmed to a preset temperature, and some even include specialized tea buttons.