The interior, while often guided by an original brief, is represented by a huge diversity of interior assemblies and typologies almost exclusively through associations with Man. The diversity of the interior is also affected by its function and relatively short lifespan. The diversity of the interior has been influenced by several art, design and architectural styles from the early part of the twentieth century and could be characterised as helping define a modern style in design. The key interior themes are Leisure, Workplace, Society, Culture, Retail and Health and Home Design. These seven master subjects cover the bulk of the interior design sector. The chapter explores the dynamics of spatial culture and how the places of the interior discipline interior have moved from servicing the internal aspects of architecture to forming a new and complete spatial culture that supports a human population which is determined and recognised globally.