A tablespoon is a non-scientific but very widely used unit of volume, which works very well in cooking, herbal medicine, etc. It is represented by a capacity of one tablespoon which varies from roughly 15 mL in the US to 20 mL in Australia.
1 If tea is properly stored, it can potentially last up to a year for green and black teas. White tea lasts about six months before it isn't as good in quality as when fresher. Stale tea (or bad tea) will taste flat, as if you're drinking paper.  Glass or ceramic containers are fine provided that they're opaque.
Steeping is the act of letting the flavour of the tea infuse into the water, and scientists claim it should be left for a minimum of two minutes. But a study has found that 80 per cent of tea drinkers can't wait that long - and 40 per cent of us drink it immediately meaning we don't get the best flavour from our cuppa.