Chinese Herbs are a major part of Chinese Medicine, and they can be thought of as having a strong and specific nourishment or anti-pathogenic effect to different areas or systems when viewed in the Chinese Medical context.
Most herbs have multiple functions, but I will describe the basic ones.
When there is poor form or looseness the astringent herbs help tone and firm.
When there is an excess of heat, moisture, cold, etc the draining herbs will drain the excess through the urine or bowels in most cases.
When there is weakness or lack of nourishment, the nourishing herbs will supplement and strengthen.
When there is hardness the softening herbs will soften and dissolve hardness or masses.
When there is stagnation or blockage of Qi and Blood, the moving herbs will move or breakup the stagnant Qi and Blood and allow nourishment in to repair the damage.
When individual herbs are combined into a formula they can accomplish many things at once.
Example: A cold manifesting with chills, clear white phlegm in the lungs, moist cough, clear runny nose with sneezing and loss of appetite and, a cold stomach to touch.
This is a Wind Cold Damp condition affecting the respiratory system mainly, but also the digestive system mildly. Herbs that expel cold wind from the surface, eliminate cold damp and phlegm from the lungs and sinuses along with herbs to eliminate dampness and cold from the digestive system.
Next lets talk about Chinese Herbs and Quality control.
All the herbal companies I use have very stringent quality control testing, from inspecting the raw herbs in China to the end product in the US. All the herbs I use are highly concentrated and processed in the traditional methods. They are a 5:1 concentration or greater, and reconstitute into a herbal tea easily, with all of the qualities as if you had cooked the raw herbs yourself but in a convenient granular form.
Click this link for a detailed explanation of the extensive quality control these companies do to ensure that you have a safe product. Chinese Herbal Quality Control