A "Back Door" refers to an alternative entrance to a building or property, typically located at the rear. This entrance is often used for service access, deliveries, or as a secondary entry point for residents. Back doors can enhance convenience and privacy, allowing people to enter without using the main entrance. In the context of technology, a "back door" can also refer to a method of bypassing normal authentication or security measures in software or systems. This allows unauthorized access, often used by developers for troubleshooting or by malicious actors for exploitation. Understanding both meanings is essential for security and practical purposes.