Terpenes are produced by all plants, including the cannabis plant. In fact, cannabis produces more than 140 different terpenes, according to ProjectCBD. 
This varied class of organic compounds can be extracted from the plant matter for the development of natural byproducts, including teas and tinctures. Terpenes are responsible for giving every cannabis variety its pleasant and unique aroma, and can be preferentially extracted from plants leaving unwanted compounds behind.
Why are terpenes extracted from cannabis?
While some people may extract terpenes to enjoy the unique aroma of a particular cannabis variety in the form of an essential oil, others may perform terpene extraction purely to treat widespread medical conditions.
Let’s take a look at the medicinal benefits of some non-psychoactive cannabis terpenes :
- Limonene – Antioxidant, anti-inflammatory and anti-cancer. 
- Myrcene – Anti-inflammatory, analgesic and anti-mutagenic. 
- Linalool – Antinociceptive and anticonvulsant. 
- α-Pinene – Anti-inflammatory and chondroprotective properties. 
- Caryophyllene – Anti-inflammatory and analgesic. 
- Camphene – Antioxidant and hypolipidemic agent. 
How are terpenes extracted from cannabis?
Generally, extraction will be carried out using one of two techniques – butane extraction or supercritical CO2 extraction. Both solvents involve the use of a closed-loop system.
There are pros and cons to the following methods of terpene extraction:
- Butane Extraction – The more dangerous of the two, butane extraction is used to develop some of the strongest byproducts on the cannabis marketplace. This technique produces flavorful terpene expression and a strong final product. With this method, butane seeps through the cannabis flower to separate terpenes from the plant material. Less environmentally friendly than CO2 extraction, oils generated from butane extractions will likely contain traces of residual solvents. However, butane terpene extractions are so fragrant that they ensure a significantly better representation of the strain aroma. 
- Supercritical CO2 Extraction – Tough on the cannabis plant, CO2 terpene extraction relies on intense pressure to strip the cannabis resin of its pungent terpenes. Phase changes are created in CO2 using pressure and temperature. There is less risk of the final product being polluted than extractions from butane. CO2-extracted oils tend to smell quite similar because they contain dominant terpenes like limonene and humulene. 
The chemical diversity of cannabis terpenes makes these fragrant oils perfect for creating industrial products, such as biofuels, lubricants, flavors, fragrances and medicines. Since the terpenes extracted from cannabis may comprise such a wide range of structures, the purity will vary based on the amount of plant material, the plant’s physical properties and the chemical properties of the targeted terpene.