Why does cannabis make you "high"?

Marijuana plants produce chemical compounds called cannabinoids. The most well known of those is delta-9-tetrahydrocannabinol (THC) and increasingly cannabidiol (CBD). THC is known to be the primary psychoactive compound in cannabis that causes the ‘high’.

When you smoke cannabis, THC goes into your lungs, then enters your bloodstream which then takes it directly to your brain. Once it's in your brain, the THC activates what are called 'receptors,' which alter normal brain communication between neurons.