Xbit: base of processors classification

[sadid]

processors classification

I've heard about 16bit,32bit and 64bit processors......
what's the base of this classification?
length of processors?
ALU?
BUS?
?
could you describe it a little for me please?
Thank

 

[sadid]

is it too hard? or maybe it is too easy to ans?

kidding! i post it again maybe this time an answer appears

 

[yasser_shoukry]

This classification is based on the internal architecture of the CPU core internal registers length. Register length affects both the length of data and address buses and the organization of the ALU.