8bit, 16bit, 32bit, what this numbers really mean..?

Most of us might already hear the term 32bit processor, 8 bit processor, AMD64, IA32, etc
We probaly know that the bigger the bit number, the better the performace of the microprocessor. But do we actually know what these bits number really mean and how it effect the overall performace of a processor..?

Processor communicate with the memory either internaly or external through what is call as address bus and data bus. The bigger the size of address bus, the bigger the memory size it can access. Example:- 16bit memory bus of 8052 microcontroller can access up to 65KB of memory.

Data bus on the other hand, is the bus that hold the data that will read or write from memory.
8bits data bus means that, at one particular read or write instruction cycle, only 8bits or 1byte can be transfer at one time.

Bits number of a processor represents the width or size of data bus

Below are list of processor or microcontroller that fall under 8bits processor:-
Intel 8088, Microchip PIC16F84A, Atmel AVR, Motorola 6800, etc

Basically it's conclude that, the bigger the data bus width, the faster the processor become because the huge number of bytes can be transfer at a time.