A memory leak occurs when a computer program fails to release memory that is no longer needed. This can happen when the program allocates memory for data but does not free it after use. Over time, these unreleased memory blocks accumulate, leading to reduced performance and potential crashes as the system runs out of available memory. Memory leaks are particularly common in programming languages like C and C++, where developers must manually manage memory. In contrast, languages like Java and Python use garbage collection to automatically reclaim unused memory, making them less prone to memory leaks. However, even these languages can experience leaks under certain conditions.