>>> import copy >>> a = [1,2,3] >>> b = a >>> b [1, 2, 3] >>> a [1, 2, 3] >>> b.pop() 3 >>> b [1, 2] >>> a [1, 2] >>> c = copy.copy(a) >>> c [1, 2] >>> a [1, 2] >>> c.pop() 2 >>> c [1] >>> a [1, 2] >>>
b=a creates only references of list (a) addresses.but copy creates entire copy of list(a).