The address in the main memory is known as the Physical Address.

Physical Address:
- The physical address refers to the actual location of a memory cell in the main memory. It is the address that is directly used by the memory management unit (MMU) to access and retrieve data from the memory.

Importance of Physical Address:
- The physical address plays a crucial role in the memory management process. It allows the operating system to locate and access specific memory locations to read or write data.
- The physical address space represents the total number of memory cells available in the main memory. Each memory cell is assigned a unique physical address.

Difference between Logical Address and Physical Address:
- Logical Address: The logical address is the address generated by the CPU or the program itself. It is independent of the physical memory layout and represents a virtual address space. Logical addresses are used for memory management purposes and are translated into physical addresses by the MMU.
- Physical Address: The physical address represents the actual location of data in the main memory. It is the address that is directly used by the MMU to access and retrieve data.

Memory Management Unit (MMU):
- The MMU is a hardware component responsible for the translation of logical addresses into physical addresses. It performs address mapping and ensures memory protection by implementing memory segmentation and paging techniques.

Conclusion:
- In summary, the address in the main memory is known as the physical address. It represents the actual location of data in the main memory and is used by the MMU for memory access and retrieval. The physical address is distinct from the logical address, which is generated by the CPU or program and needs to be translated into a physical address by the MMU.