<human>:  When a substance is oxidized, what is it oxidized to?
<bot>: When a substance is oxidized, it is oxidized to a substance called a reducing agent. A reducing agent is a substance that can be reduced, or turned into a different substance. For example, when you burn a piece of paper, the paper is oxidized to carbon dioxide and water. The carbon dioxide is a reducing agent, and can be reduced back to carbon.