Patio doors are large openings that connect indoor living spaces to outdoor areas, such as patios or decks. They are typically made of glass and can slide or swing open, allowing for easy access and natural light. Common types include sliding glass doors and French doors, each offering different aesthetic and functional benefits. These doors enhance the flow between the inside and outside of a home, making spaces feel larger and more inviting. They also provide views of the outdoors and can improve ventilation when opened. Proper installation and maintenance are essential for energy efficiency and security.