Biophilic Design
Some hospitals have measured shorter patient recovery times simply from adding more natural light and greenery to the rooms.
Color Theory in Design
Many designers split a room's colors 60-30-10: a dominant shade, a secondary one, and a small pop of accent.
Feng Shui
A design philosophy old enough to predate most architecture as we know it, still influencing exactly where people put their beds and desks today.
Maximalism (Interior Design)
Where minimalism asks what a room can live without, maximalism asks how much personality it can actually hold.
Minimalism
Minimalism says own less, yet nailing the look can mean buying a lot of carefully curated new things.