Energon is the preferred fuel of the Transformer race. It takes many forms, including ore, crystal, gas, and raw energy, but it is most commonly used by Transformers in its liquid state, which is stored in many different mediums, most famously the energon cube. It is ubiquitous in Cybertronian culture; in addition to being the Transformers' primary "foodstuff", it also serves as the default power source for their machines and weapons, and is even used as a currency, a catch-all fuel of life, technology, war and commerce on Cybertron and beyond. This widespread use also comes in defiance of its extreme volatility: energon is prone to detonating explosively if mishandled, and is even used as ammunition in order to exploit this attribute.
Energon is an emanation of Primus, and a different form of that which makes up a Transformer and everything else on Cybertron. Energon occurs naturally in the form of blue crystals, though these sometimes resemble normal rocks. It is stored within Energon cubes, the framework for which can be produced by the Decepticon Soundwave, and is fashioned into smaller ingots for oral ingestion by Transformers. It also has a dark counterpart called Dark Energon.