CBD is an abbreviation for cannabidiol.
The first form is CBD isolate. This is the purest form of CBD literally isolated cannabidiol. This is a white crystalline powder it is derived from the refinement of CBD Distillate.
This is second form which is CBD distillate, also known as Full Spectrum CBD. The distillate has many more cannabinoids than the singular CBD isolate. Including and not limited to CBD and CBDa CBH CBN and less than .3% THC. In this form is still very pure, but also very viscous sticky resinous oil.
A common non-intoxicating compound produced by cannabis, with a wide range of medical applications.
CBD is the second most commonly produced compound in cannabis varieties bred for their medicinal use, and the most common in varieties bred for agriculture (commonly known as hemp). It is of interest to many people for its medicinal value, especially its anti-epileptic, anti-anxiety, and anti-inflammatory effects.
Summary from Wikipedia:
Cannabidiol (CBD) is a phytocannabinoid discovered in 1940. It is one of some 113 identified cannabinoids in cannabis plants and accounts for up to 40% of the plant’s extract. In 2018, clinical research on cannabidiol included preliminary studies of anxiety, cognition, movement disorders, and pain.
Cannabidiol can be taken into the body in multiple ways, including by inhalation of cannabis smoke or vapor, as an aerosol spray into the cheek, and by mouth. It may be supplied as CBD oil containing only CBD as the active ingredient (no included tetrahydrocannabinol [THC] or terpenes), a full-plant CBD-dominant hemp extract oil, capsules, dried cannabis, or as a prescription liquid solution. CBD does not have the same psychoactivity as THC, and may affect the actions of THC. As of 2018, the mechanism of action for its biological effects has not been determined.
In the United States, the cannabidiol drug Epidiolex was approved by the Food and Drug Administration in 2018 for treatment of two epilepsy disorders. The side effects of long-term use of the drug include somnolence, decreased appetite, diarrhea, fatigue, malaise, weakness, and sleeping problems. As of April 2019, CBD extracted from marijuana remains a Schedule I drug classification, and is not approved as a prescription drug, dietary supplement, or allowed for interstate commerce in the United States.
Project CBD is a very comprehensive resource