The heap is an area of memory that your program uses when it wants to dynamically allocate space for data. While using the heap gives you a considerable amount of flexibility, your program must manage this resource. That is, the program must explicitly allocate and deallocate this space. In contrast, the program does not allocate or deallocate memory in other areas.
Because allocations and deallocations are intimately linked with your program’s algorithms and, in some cases, the way the program uses this memory is implicit rather than explicit, problems associated with the heap are the hardest to find.