It is fine ground powder of special green tea leaves, called tencha.
Tencha is a tea leaf that is harvested in a special way. To make tencha, the tea plants are covered for more than 20 days before picking up the tea leaves so that the plants try to grow faster to get sunlight, using their energy to grow instead of thickening their leaves. This results in thin and soft leaves, that add a lot of flavor to the tea.
The leaves are then left to dry, without rolling. Stems and leaf veins are discarded.
Matcha contains a type of potent antioxidant called EGCG (epigallocatechin gallate) that has cancer-fighting properties and help decrease several heart-related diseases.
Matcha has properties that boost metabolism and burn fat.
Matcha is very rich in aminoacids that help reduce stress and enhance relaxation.
It is proven to increase memory.