Trigger finger, or stenosing tenosynovitis, is a condition where one of the fingers gets stuck in a bent position and then straightens with a snap, like a trigger being pulled and released. It occurs when the tendon sheath in the affected finger becomes inflamed or swollen, causing it to catch or lock when trying to straighten the finger. Symptoms may include pain, stiffness, and a popping sensation when moving the affected finger. Trigger finger is more common in individuals who perform repetitive gripping motions or have certain medical conditions like diabetes or rheumatoid arthritis.