The houses are twelve divisions of the chart that map planetary positions onto specific domains of life. Where the signs describe the quality or style of a planet's expression, the houses describe the area of life in which that expression shows up. A Mars in Scorpio in the second house behaves very differently from a Mars in Scorpio in the eighth house, even though the sign and planet are the same — the house is the address.
The traditional twelve houses correspond to: 1st (self, body, identity), 2nd (money, possessions, values), 3rd (communication, siblings, short trips), 4th (home, family, roots), 5th (creativity, romance, children), 6th (work, health, daily routines), 7th (partnership, marriage, open enemies), 8th (transformation, shared resources, death and rebirth), 9th (philosophy, travel, higher learning), 10th (career, reputation, public role), 11th (friendships, groups, hopes), 12th (the unconscious, hidden things, retreat).
The house cusps are calculated using a house system, of which there are several. The most common in modern Western astrology are Placidus, Whole Sign, Equal House, and Koch. Each system divides the chart in a different way, and the same planet can fall in different houses depending on the system used. ZODIA uses the Placidus system by default, which is the most widely adopted in modern Western practice.
A planet placed close to a house cusp can be ambiguous, and a few degrees of birth time error can move a planet from one house to its neighbor. This is one of the reasons accurate birth time matters so much: the houses are the most birth-time-sensitive layer of the chart.
See These Concepts In Your Own Chart
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