All under the sun ( :-)

http://www.esabna.com/EUWeb/AWTC/Lesson1_8.htm

Nice welding tutorial with videos
http://www.mig-welding.co.uk/arc-tutorial.htm

Diff between various weldings
http://www.mig-welding.co.uk/arc-tutorial.htm

Some more explanation too
http://reviews.ebay.com.au/Buying-a-welding-machine-on-eBay?ugid=10000000001235640