Cannabinoids are a family of natural compounds made by the cannabis plant. Scientists have identified more than a hundred of them. The best known are THC, the main intoxicating one, and CBD, which is not intoxicating. Others you will see on labels include THCA, CBG, CBN and CBC.
These compounds interact with the endocannabinoid system, a signaling network that exists in the human body. Its main receptors are called CB1 and CB2. THC, for example, binds to CB1 receptors in the brain, which is a big part of why it causes a "high." Other cannabinoids interact with the system in different and sometimes weaker ways.
In the raw plant, most cannabinoids exist in an "acid" form, such as THCA and CBDA. Heat converts these acids into their active forms in a process called decarboxylation. That is why lab reports list both THCA and delta-9 THC, and why labels often show a calculated "total THC."
On a certificate of analysis, the cannabinoid section shows how much of each compound is in the product, either as a percentage (for flower and concentrates) or in milligrams (for edibles and tinctures). Reading that section helps you compare products more accurately than names or labels alone.