Locking, or lock, is a mechanism used to secure doors, containers, or devices, preventing unauthorized access. It typically consists of a metal bolt that can be engaged or disengaged using a key, combination, or electronic code. Locks come in various types, including padlocks, deadbolts, and smart locks, each designed for specific security needs. In computing, locking refers to a method of controlling access to shared resources in a multi-threaded environment. When a program locks a resource, it prevents other threads from accessing it simultaneously, ensuring data integrity and preventing conflicts. This is crucial in applications where multiple processes may attempt to read or write data at the same time.