CBD (cannabidiol) is a cannabinoid derived out of the cannabis family, its non-psychoactive meaning there is a lack of the euphoria or "high", unlike its cousin (THC) tetrahydrocannabinol. CBD does not use the same receptors as THC it activates or inhibits other compounds in the endocannabinoid system.
I.E, CBD stops the body from absorbing anandamide, a compound associated with regulating pain. So, increased levels of anandamide in the bloodstream may reduce the amount of pain a person feels.
Broad-spectrum CBD is just like any other full-spectrum CBD, it is sourced from hemp plants of the highest quality which are rich in high-quality cannabinoids and terpenes. The only thing that separates broad-spectrum from full-spectrum is that with the former, THC is removed or processed out of the extract using a special chromatography media. This leaves an extract devoid of THC but still full of other cannabinoids, terpenes, and other plant matter.