[cpburns2009]

urllib and urllib2 are built-in for Python 2, and were merged and reorganized as just urllib in Python 3. urllib3 is a third-party module.

[haikuginger]

This is correct. In general, though, most packages don't rely on urllib3 directly, but on `requests`, which uses urllib3 but provides a friendlier API and built-in SSL cert verification.