Herbal therapy as the name suggests is the process of herbs and their essences to aid in the cure of specific ailments. Nature has always provided for solutions to all possible ailments including the ability to grow tissues, activate nerve transmissions etc. Most herbs are safe to use in that they rarely have impacting side effects, unlike chemical drugs.
Considerable research has gone into the use of specific herbs or plants in curing specific ailments and historical evidence chronicled on which reliance can be placed. While Ayurveda is an advanced form of herbal therapy, there are simpler solutions to many common ailments. Different parts of the plant/shrub/tree like stems, roots, leaves, flowers are used in the process of treatment. They are administered directly, as decoction, as tincture, as elixir, or processed in the form of tablets or capsules.
Adaptogens are special kind of herbs that aids the body to restore homeostatis.
Many of the herbal medicines are now available in standard chemists shops and often in easy to consume format like tablets, powders, liquids and capsules.