by Angela Errett | What is a door? Anyone reading this knows that a door is a passageway from one space into another. It is a doorway, a gate, you must go through to get from one room to another or from the “outdoors” into the “indoors.” Everywhere you look, there are doors; front doors, back doors, side doors, attic doors. A door on your car. A door on the bus. A door on every building you pass on the street.