The 12 Houses
The twelve bhavas map life's terrain: self, wealth, siblings, home, children, service, partnership, transformation, fortune, career, gains and release.
Kendras and trikonas
Houses 1, 4, 7 and 10 (kendras) are pillars of action; 1, 5 and 9 (trikonas) are the fortune triangle. Planets and lords bridging both create the classical Raja yogas.
Dusthanas
Houses 6, 8 and 12 handle debt, transformation and loss. Placements here are demanding rather than damning — many charts of surgeons, researchers and monastics lean on them.