What is all this about 'debugging'

Hello,

I now know enough about Articulate and Moodle to make me dangerous.  I can solve some problems but seem to create many more.

How does debugging work into all of this?  I have seem several threads about HTTP Watch, Firebug, Test Suite, etc....

When would I need to delve into these and what tool is best for what?  Any help or ideas are always appreciated...

Cheers,

Dave