Capsule endoscopy was first used in humans in 1999 and approved by the FDA in 2001. It has become a valuable tool for investigating gastrointestinal diseases. The capsule consists of lenses, LEDs, batteries, and an imaging sensor that transmits thousands of images as it passes through the digestive tract. Preparations may include laxatives or other medications. Complications are rare but include capsule retention. Technical improvements continue to enhance image quality and navigation capabilities. Future directions include remote-controlled and self-propelled capsules.