* Oxidation involves the loss of electrons and often results in the gain of oxygen atoms or the loss of hydrogen atoms.

* Reduction involves the gain of electrons and often results in the loss of oxygen atoms or the gain of hydrogen atoms.

In fermentation:

* A sugar molecule (like glucose) is broken down, but it's not fully oxidized to carbon dioxide like in aerobic respiration.

* Instead, the sugar is partially oxidized, and some of its electrons are transferred to another molecule, usually a derivative of the sugar itself.

* This transfer of electrons to another molecule is a reduction process.

Example:

In alcoholic fermentation, glucose is converted to pyruvate, then to ethanol. The pyruvate is reduced to ethanol, gaining electrons and hydrogen atoms in the process.

Key Takeaway: While fermentation does involve some oxidation, the overall process is driven by reduction reactions, as electrons are transferred to other molecules.