TimeOut

1. Camellia sinensis var. sinensis makes up most Chinese, Formosan, Japanese and Darjeeling teas
2. Camellia sinensis var. assamica is used in Pu-Erh and many Indian (Assam) teas

Tea plants grow from seed or cuttings, and must mature about three years before their leaves are first harvested.  They need very warm, very wet climate conditions, and so are grown primarily in near the equator on elevated slopes where more than 1.5 meters of rain falls each per year. Some well-known tea producing areas include China, India, Sri Lanka, Kenya, Japan, etc.

Only the top few centimeters of the branch tips are picked. When a tea plant produces new buds and leaf tips, it is called a "flush". In some areas, like Darjeeling, teas are offered from Spring (first), Normal (second), and Autumn (third) flush. Flavor in a tea comes from the particular variety of plant, the location of the plantation and specific processing styles, but the flushes also affect taste in a distinctive way. As you might distinguish a clean, crisp New Zealand grassy Sauvignon Blanc from a viscous, oaky California malolactic-fermented Chardonnay, so you can tell an astringent, floral spring flush from a dusky, musky autumn flush. 

I think tea is much like wine in its reflection of the terroir or environment in which it is grown. An individual variety can be quite different year-to-year (vintage). Here are some of the varieties that I have sampled: 

After  tea leaves are picked, they are carefully dried. During the drying process, the leaves become darker and tannins concentrate. The leaves oxidize and may ferment. At the right moment, heat is applied (under the drying table, or in a drying room) and the fermentation process stops. 

The amount and timing of drying and heat are very carefully controlled, and determine whether tea is sold as white, green, oolong, black or fermented. After the fermentation has halted, the leaves are sorted, graded, blended (with each other, flowers, herbs) and then flavored or scented (oils, flavors, spices, etc), and/or smoked.