science concept behind rusting

It's a state ... a slow acting oxidation.

http://en.wikipedia.org/wiki/Rust

As Ragman said it is oxidation but it is in cases a special type of oxidation as rusting involves metals. Think of batteries and half cell reactions. There are three ways of preventing rust, of which two are electrical.

The first is coating--protect the metal. The second is anodic protection--impart a slight electrical charge greater than the half cell reaction (oxidation) of the metal you're protecting. The third is sacrificial protection, this is to introduce another metal with a half cell reaction greater that the metal you're trying to protect.

Essentially the second and third method are the same, but the second is considered active protection while the third is considered passive protection.

BTW the 50cent word for rusting is electrodisposition.

Rap

Rust Never Sleeps

I'm afraid my chemistry is a little rusty.