Dynamic memory allocation is the process of assigning memory space during the execution time or run time. It is used to manage memory more explicitly and flexibly, typically by allocating it from the free store, an area of memory structured for this purpose. In C programming, dynamic memory allocation is performed using a group of functions in the C standard library, namely malloc, realloc, calloc, aligned_alloc, and free.

Dynamic memory allocation is useful when neither static- nor automatic-duration memory is adequate for all situations. Automatic-allocated data cannot persist across multiple function calls, while static data persists for the life of the program whether it is needed or not. In many situations, the programmer requires greater flexibility in managing the lifetime of allocated memory.

The following are the four library functions provided by C defined under the <stdlib.h> header file to facilitate dynamic memory allocation in C programming:

• malloc(): used to dynamically allocate a single large block of memory with the specified size.
• calloc(): used to dynamically allocate the specified number of blocks of memory of the specified type.
• free(): used to deallocate the memory previously allocated by malloc() or calloc().
• realloc(): used to change the size of the previously allocated memory.

Dynamic memory allocation can be a source of bugs if not used properly. Common errors include not checking for allocation failures, accessing memory that has already been freed, and not freeing memory that has been allocated.