A thumb turn lock is a type of locking mechanism commonly used on doors. It features a rotating cylinder that can be turned with a thumb, allowing for easy locking and unlocking from the inside without needing a key. This design is convenient for quick access and is often found in residential settings. These locks are typically installed on interior doors, such as bathrooms or bedrooms, where privacy is desired. While thumb turn locks provide ease of use, they may not offer the same level of security as traditional keyed locks, making them less suitable for exterior doors.