Dynamic memory allocation 
Allocation in the heap (or dynamic allocation) is common in programming. We need dynamic allocation for the flexibility to allocate at runtime. The operating system implements the dynamic memory management structures, algorithms, and routines. All dynamically allocated memory goes to the heap section of main memory. The OS maintains a few linked lists of memory blocks, primarily the free list to track contiguous blocks of free/unallocated memory and the allocated list to track blocks that have been allocated to the applications. On new memory allocation requests (malloc()/new), it traverses the free list to find a block free enough, then updates the free list (by removing that block) and adds it to the allocated list and then returns the memory block to the program. On memory deallocation requests (free()/delete), it removes the freed block from the allocated list and moves it back to the free list.