NameError: name 'raw_input' is not defined

It worked well at school, but it doesn't work when I get home. It says raw_input is undefined, what's wrong?

import sys
print (sys.platform)
print (2 ** 100)
raw_input()

Traceback (most recent call last): File "/Users/hoj/PycharmProjects/mine.py", line 1, in raw_input()