While the ideal water temperature for different types of tea varies, the practical reality is that in everyday situations such a level of perfection may be hard to achieve.
However, as general rule, whatever the tea being infused, the temperature should never be more than the immediate point of boiling (approx. 95C).
Water temperature that is higher than this will scald the leaves, destroy the aroma and the tea will taste bitter. So do not overboil the water.
Conversely if the water is not hot enough it will prevent the leaves from releasing their full flavour.
Green and white teas are best infused with water that is just before the point of boiling.