What's the reference and reference count in python?

Answer 1

Python deletes data objects automatically after they fall out of use.
For that reason Python keeps track of how many 'names' that object has.
a = [1, 2, 3] # list created, ref count 1
b = a # ref count 2
c = {'list': a} # ref count 3
del a # one name deleted, rc 2
del c['list'] # ref count 1
b = 42 # name b given to something else; original list's ref count now 0. Python is free to delete the object.