Doors are swinging, sliding, or revolving barriers located at the entrance to buildings and other spaces. Their primary function is to allow people the ability to enter and leave, securing a way of passage. A secondary function is to provide a sense of privacy through the separation of areas within a building. Doors can control the amount of light, ventilation, and noise of a room or space. There are a variety of types of doors that differentiate in terms of operability, accessibility, materiality, etc.
The invention of the door is not a specific date, but it is believed that the concept of a barrier for openings has been used for thousands of years by different cultures around the world. The earliest known doors were made of stone, dating back to ancient Egyptian tombs around 2000 BCE. Doors made of wood and other materials were also used in ancient civilizations such as Greece and Rome.
The Tallest door in the world is from the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida, USA. The VAB door stands at a height of 456 feet (139 m) and width of 135 feet (41 m). It is one of the largest single-panel doors in the world, and it was designed to allow the assembly and servicing of the Saturn V and Space Shuttle rockets. It is a significant architectural feature and a symbol of the space program's technological capabilities.
Some cultures traditionally do not use doors in the way that they are commonly used in Western cultures. For example, the Himba people of Namibia, Africa traditionally do not use doors in their homes. Instead, they use low walls made of mud, stone, or wood to separate different areas within their homes. Similarly, the nomadic people of the Mongolian steppe have traditionally used felt and canvas tents as their homes, which do not have doors.