Augmented reality (AR) is a technology that overlays digital information and objects onto the real world. The document discusses the history of AR from early concepts in the 1960s to recent frameworks like ARKit and ARCore. It explains how AR works by overlaying computer-generated images onto see-through displays. Examples of AR applications include using it in education, medicine, gaming, and military operations. The benefits of AR include enhanced learning and situational awareness, though it faces drawbacks like over-reliance on digital information and privacy concerns.