I recently purchased a toy for my son on Ebay that runs on salt water I guess it works on a chemical reaction with magnesium. Anyway the description was very broken english and I would like to know what this technology is called and any information you might deem relevant so I can find a "blurb" online in order to explain to him how and why it works and what else it is used for.

It's probably the same battery as described in these products; they have a very general description of the reaction

 

http://www.engadget.com/2012/09/06/green-houses-lantern-runs-on-salt-water-usb/

http://www.jameco.com/Jameco/content/saltwater.html

 

I'd search on "salt water" magnesium carbon battery or similar terms to find more

 

This example uses iron instead of carbon for one of the electrodes

http://www.miniscience.com/projects/Airbattery_Advanced/index.html