What are the differences between the urllib, urllib2, urllib3 and requests module?

Question

In Python, what are the differences between the urllib, urllib2, urllib3 and requests modules? Why are there three? They seem to do the same thing...

Answer 1

You should generally use urllib2, since this makes things a bit easier at times by accepting Request objects and will also raise a URLException on protocol errors. With Google App Engine though, you can't use either. You have to use the URL Fetch API that Google provides in its sandboxed Python environment.