We all know about tetrahydrocannabinol, or THC: the magical chemical in marijuana that interacts with the cannabinoid receptors in the brain, altering our sense of pleasure, time perception, and memory.

Less commonly understood, however, are the other compounds in cannabis that effect the brain - most notably, CBD. CBD-rich cannabis has been used to relieve pain, reduce inflammation, and treat serious illnesses including epilepsy, diabetes, and arthritis. But what is it, and why is it being hailed as a miracle treatment? Here are five things you need to know.

1. It doesn't get you high

Although some studies claim CBD, or cannabidiol, has anti-inflammatory, anticonvulsant, and neuroprotective qualities, can reduce brain and breast cancer cell proliferation and even slow the development of Alzheimer's disease - unlike THC, CBD doesn't produce any euphoric, hazy, mind-altering effects. "I do not get high from CBD," writes one Erowid contributor. "It's kind of like being stoned but without the head change."

2. It works with THC

CBD reportedly increases the duration of a THC high, and, with THC, also reportedly stimulates neurogenesis, the creation of new brain cells, in adult mammals. Although CBD and THC act on different pathways of the body," according to LeafScience, "they seem to have many of the same medical benefits." Some have dubbed this the "entourage effect" - and rightly so, given that CBD is just one of an estimated 80 active cannabinoid chemicals in the plant.

3. You don't have to smoke it

While you smoke CBD strains like CBD OG just like you would any other weed, CBD products that are applied topically, vaporized, or taken in capsule form have undergone a recent surge in popularity. By choosing consumption methods other than smoking, you can unlock the maximum, chilled-out effects of CBD - without exposing your lungs to harmful smoke.

4. It's legal in a lot of places

Good news: if CBD products are manufactured using hemp, they're legal in any state: agricultural hemp, unlike cannabis, is not a controlled substance. "To date," according to NIDA, 23 states and the District of Columbia have passed laws allowing marijuana to be used for a variety of medical conditions. Fifteen additional states have enacted laws intended to allow access to CBD oil and/or high-CBD strains of marijuana."

5. It's not that well-understood (yet)

CBD, according to the National Institute on Drug Abuse, is a "critical area for new research:" a relative lack of well-controlled, human clinical trials are available. "Furthermore," adds NIDA, "the opportunity to gather important information on clinical outcomes through practical (non-randomized) trials for patients using CBD products available in state marijuana dispensaries is complicated by the variable quality and purity of CBD from these sources." In other words: until government restrictions on clinical trials involving cannabis are eased, folks need to be careful not to let enthusiasm get ahead of the evidence.

Banner image: close up of a small capsule filled with a dark oil produced from the hemp plant as a medicinal marijuana concept, (Wollertz, Shutterstock.com)