What is the difference between THCA and Delta 9 THC?

THCA is the acid form of THC and is non-psychoactive until heated. Once THCA is decarboxylated (smoked or vaped), it turns into Delta 9 THC—the active compound that produces a high. The key difference is that THCA is legal under hemp laws when under 0.3% Delta 9 THC by dry weight, making it a legal way to enjoy cannabis-like effects.