Decoction: A tea made from boiling plant material, usually the bark, rhizomes, roots or other woody parts, in water. May be used therapeutically. Natural dyes are oftenmade this way. 

Infusion: A tea made by pouring water over plant material )usually dried flowers, fruit, leaves, and other parts, though fresh plant material may also be used), then allowed to steep. The water is usually boiling, but cold infusions are also an option. May be used therapeutically, as hot tea is an excellent way to administer herbs. 

Tincture: An extract of a plant made by soaking herbs in a dark placewith a desired amount of either glycerine, alcohol, or vinegar for two to six weeks. The liquid is strained from the plant material and then used therapeutically. (This is Your Personal Herbalist's favorite.)

Liniment: Extract of a plant added to either alcohol or vinegar and applied topically to employ the therapeutic benefits. 

Poultice: A therapeutic topical application of a soft moist mass of plant material (such as bruised fresh herbs), usually wrapped in a fine woven cloth. 

Essential Oils: Aromatic volatile oils extracted from the leaves, stems, flowers, and other parts of plants. Therapeutic use generally includes dilution of the highly concentrated oil. 

Herbal Infused Oils: A process of extraction in which the volatile oils of the plant substance are obtained by soaking the plant in a carrier oil for approximately two weeks and then straining the oil. The resulting oil is used therapeutically and may contain the plant's aromatic characteristic.