"Lock-free" refers to a type of concurrent programming design that allows multiple threads to operate on shared data without using traditional locking mechanisms. This approach helps to avoid issues like deadlocks and reduces the time threads spend waiting for access to resources, leading to improved performance in multi-threaded applications. In a lock-free system, at least one thread can make progress in a finite number of steps, ensuring that the system remains responsive. Common techniques used in lock-free programming include atomic operations and compare-and-swap algorithms, which help manage shared data safely without the need for locks.