Memory leak
In computer science, a memory leak is a type of resource leak that occurs when a computer program incorrectly manages memory allocations in such a way that memory which is no longer needed is not released. In object-oriented programming, a memory leak may happen when an object is stored in memory but cannot be accessed by the running code. A memory leak has symptoms similar to a number of other problems (see below) and generally can only be diagnosed by a programmer with access to the program's source code.
Because they can exhaust available system memory as an application runs, memory leaks are often the cause of or a contributing factor to software aging.
Consequences
A memory leak can diminish the performance of the computer by reducing the amount of available memory. Eventually, in the worst case, too much of the available memory may become allocated and all or part of the system or device stops working correctly, the application fails, or the system slows down vastly due to thrashing.