The most common method of drying is to extract moisture in the form of water vapour. To do this, heat must be supplied to the wood to provide the latent heat of vaporisation. There are several ways of conveying heat to the wood and removing the evaporated moisture.

Nearly all the world's timber is, in fact, dried in air. This can be carried out at ordinary atmospheric temperatures (air drying), or in a kiln at controlled temperatures raised artificially above atmospheric temperature but not usually above 100°C, the boiling point of water. Air drying and kiln drying are fundamentally the same process because, with both, air is the medium which conveys heat to the wood and carries away the evaporated moisture.