One unique characteristic of green tea leaf is that since it undergoes less oxidation and are steamed the leaves retain their herbal freshness, mellow taste and aroma.
Green teas which have gained a lot of popularity all over the World are:
Sencha - Japan
Macha - Japan
Darjeeling Green Tea - India
Though green teas have their own characteristic flavor there is a commonality which is basic of all the green tea leaves. While brewing green tea loose leaf is preferred since one has to constantly work to immerse the green tea bags to extract poly phenols rather then let it afloat.
The poly phenol amount increases in the brew if the leaves are steeped for a longer time and the brew does not reach the boiling point during the tea making.