Rising hot air, and the absence of oxygen created by the combustion process, pulls air through the bottom vents holes. This movement fuels the fire at its base while also providing a boost of preheated air through the vent holes at the top of the burn chamber.
Designed with a double wall, the Solo Stove is a natural convection inverted downgas gasifer stove. The air intake holes on the bottom of the stove channel air to the bottom of the fire while at the same time, channels warm air up between the walls of the stove. This burst of preheated oxygen feeding back into the firebox through the smaller holes at the top of the stove causes a secondary combustion. This allows the fire to burn more complete which is why there is very little smoke during full burn. A more efficient burn also means you'll use much less wood compared to an open camp fire.
The Solo Stove doesn't just burn wood. It actually cooks the smoke out of the wood and then burns the smoke not once, but twice! The cooking ring's angled lip also increases efficiency by directing heat towards your pot minimizing heat loss. It also acts as a windshield while still allowing oxygen to flow inward. The Solo Stove is indeed one of the most efficient wood burning stoves you'll ever own.