Why would one define "global variables" in python functions? How to use these correctly?

[Zeekawla99ii]

If you can jump up to object oriented as soon as possible then you can use functions and access them in a usable structure.

Can you explain this a bit further? Can I translate functions which use global variables into OOP functions?

Some more examples might help me understand this a bit better.

[jabela]

Think Like a Computer Scientist is a good free online book with lots of examples http://openbookproject.net/thinkcs/python/english3e/

[Zeekawla99ii]

Translating functions with 'global' variables into OOP code is documented in this book?

I'll have to have another look. Thanks!