A CBD pen is a small, pen-shaped vaping device used to inhale CBD oil, offering a fast-acting way to potentially promote relaxation and calm without the "high" of THC, available in convenient disposable or refillable versions with various CBD types (like full-spectrum) and flavors. Users inhale vaporized CBD, which quickly enters the bloodstream, with many reporting reduced anxiety and tension, but it's crucial to choose reputable brands with third-party lab results for safety and effectiveness.