Difference between physical/logical/virtual memory address

Question

I am a little confused about the terms physical/logical/virtual addresses in an Operating System(I use Linux- open SUSE)

Here is what I understand:

Answer 1

Physical Address is the address that is seen by the memory unit, i.e., one loaded into memory address register. Logical Address is the address that is generated by the CPU. The user program can never see the real physical address.Memory mapping unit converts the logical address to physical address. Logical address generated by user process must be mapped to physical memory before they are used.