What does it mean to invert a sponge cake?

To invert a sponge cake means to turn it upside down after baking, typically while it's cooling. This technique is used to prevent the cake from collapsing and to help maintain its airy texture. Inverting the cake allows gravity to keep the structure intact, ensuring a light and fluffy result. It is often done using a tube pan, where the cake is left to cool suspended, allowing the steam to escape and preventing it from becoming soggy.