- "Always another way."
- ―The Keymaker [src]
A backdoor is a type of door that can be used to access nearly any part of the Matrix.
Within the construct, they aren't a series of light blue doors in a seemingly endless white corridor(I see the end right there), unlocked by a special made key. These were used by Programs to quickly get from one place to another. In code, these were simply loopholes. At one end of the corridor was a door to the most special rooms, including the door to The Source. Backdoors act as a kind of shortcut hyperlinking system.