Memory Management Unit (MMU) protects the memory from unauthorized access and ensures that the memory is used efficiently. It is a hardware component that is responsible for managing the virtual and physical memory and translation between them. The MMU is an essential component of the CPU that has a significant role to play in the efficient functioning of the system.

The following are the functions of the MMU:

1. Memory Protection: The MMU protects the memory from unauthorized access. It ensures that only authorized programs can access the memory and that no program can access the memory of another program.

2. Memory Mapping: The MMU maps the virtual memory to the physical memory. It translates the virtual address generated by the program to the physical address of the memory.

3. Memory Sharing: The MMU enables memory sharing between programs. It allows multiple programs to share the same memory space without interfering with each other.

4. Memory Allocation: The MMU manages the allocation of memory to the programs. It ensures that the memory is allocated efficiently and that there is no wastage of memory.

5. Memory Paging: The MMU manages the paging of memory. It divides the memory into pages and loads only the required pages into the RAM, thereby reducing the memory usage.

In summary, the Memory Management Unit (MMU) is responsible for managing the virtual and physical memory and translation between them. It protects the memory from unauthorized access, maps the virtual memory to the physical memory, enables memory sharing between programs, manages the allocation of memory to the programs, and manages the paging of memory.