Windows are openings in walls designed to admit natural light, provide ventilation, and offer views to the outdoors. Made from glass set within frames of wood, vinyl, aluminum, or composite materials, they play a vital role in energy efficiency and indoor comfort. Modern windows often feature double or triple glazing, low-emissivity coatings, and insulated frames to reduce heat transfer and lower energy bills. They are engineered for weather resistance, sound insulation, and ease of operation, with options like casement, double-hung, and sliding styles to suit different architectural needs. Proper installation ensures air-tight seals to prevent drafts and moisture intrusion. Windows also enhance safety with tempered or laminated glass options and may include built-in screens for insect control. Thoughtfully placed windows can improve natural lighting, reducing reliance on artificial sources and creating more pleasant, healthy indoor environments. Their design balances aesthetics, functionality, and sustainability in every building project.