A Memory Leak occurs in software when a program improperly manages memory allocations, causing it to retain memory that is no longer needed, without releasing it back to the system. Over time, the program consumes more and more memory, which can degrade performance or eventually cause the system to crash. Memory leaks are common issues in applications written in languages like C or C++, where developers manually manage memory allocation and deallocation. In languages with automatic garbage collection, like Java or Python, memory leaks can still occur, but they are less frequent.

The main causes of memory leaks include:

Failure to Deallocate Memory: A program allocates memory for objects or data structures but does not properly release it when it's no longer needed.
Circular References: Objects in memory reference each other in a cycle, preventing the memory management system from recognizing that they can be deallocated.
Unnecessary Retention of Objects: Objects are kept in memory for longer than needed due to poor programming practices or incorrect logic.
Memory leaks can lead to significant performance issues, particularly in long-running applications like servers or embedded systems. Over time, memory consumption increases, leading to slowdowns, high memory usage, and, eventually, system crashes.

To detect and fix memory leaks, developers use tools like valgrind, gdb, or memory profilers. Fixing memory leaks usually involves carefully auditing the code, ensuring that memory is properly deallocated when no longer needed.

In summary, a Memory Leak occurs when an application fails to release memory that it no longer needs, gradually degrading performance and potentially causing system failure. Proper memory management practices and tools can help detect and fix memory leaks, ensuring stable and efficient software performance.