We often consider architecture and the object through the full, the tangible property, as this is the first visual thing presented to us. However, the empty is essential and complementary, and a key concept for the interior architect: it is the very substance of the space into which we inject uses and atmospheres, it is the negative of plans. The empty is much more than just an elusive absence, it has a multitude of facets. This dissertation attempts to decrypt the abundance of the empty by analysing its many different territories, its design methods and uses.