Actually, it's a bit more complicated: for small integers, the Python runtime has a stash of pre-made objects. For compiled code, the code may include a static

Actually, it's a bit more complicated: for small integers, the Python runtime has a stash of pre-made objects. For compiled code, the code may include a static reference to a constant object. Which means that, if you execute "a = 110" a bunch of times, no new objects get created. If you execute "a= 110+300" a bunch of times, a whole bunch of new objects is created and destroyed. By the way, this boxing/unboxing logic is also at work when you stick numbers into a standard HashMap, since it stores Integer objects and not the primitive type. However, in Java you can use GNU Trove's IntObjectHashMap or ObjectIntHashMap and save some memory, whereas Python's "everything is an object" rules this out (unless you're using PyPy and its tracing jit which figures out that a always contains a number).