What the houses are
A birth chart is the sky at the moment you were born, seen from where you were born. The twelve houses divide that sky, starting from the eastern horizon, into twelve areas of life. They are counted counterclockwise around the chart from the Ascendant, the point rising in the east, and each begins at a line called its cusp. In Placidus, this site's default, the 1st, 4th, 7th and 10th houses begin exactly at the four angles; in Whole Sign houses each house is one whole sign instead.
Planets describe what is at work, signs describe how, and houses describe where: Venus in Libra in the 10th house is charm and balance, brought to career and reputation. Because the whole circle of houses turns once a day, they depend on your exact birth time and place. Your birth chart shows your houses and which planets sit in each.
The first house: self, body and first impressions
The 1st house begins at the Ascendant, your rising sign. It covers your body, appearance, temperament and the way you meet the world: the first impression before anyone knows you. Planets here are read as prominent in your personality. It is naturally linked with Aries and Mars. Your rising sign sits on its cusp.
The second house: money, possessions and self-worth
The 2nd house covers what you own and earn, and what you value, including your sense of your own worth. Planets here are read as shaping how you handle money and security. It is naturally linked with Taurus and Venus.
The third house: communication, siblings and daily travel
The 3rd house covers everyday thinking and talk: writing, learning, short trips, neighbors, and brothers and sisters. It is naturally linked with Gemini and Mercury.
The fourth house: home, family and roots
The 4th house begins at the IC, the lowest point of the chart. It covers home, family, ancestry and your private life, and it is read as the foundation everything else rests on. It is naturally linked with Cancer and the Moon.
The fifth house: romance, creativity, children and fun
The 5th house covers what you do for joy: dating and romance, creative work, play, hobbies and children. It is naturally linked with Leo and the Sun.
The sixth house: work, health and service
The sixth house in astrology covers daily life and the body's upkeep: your work routines and duties, habits, health, service to others, pets and the people you work alongside. Where the 10th house is your career and public standing, the 6th is the job itself, day by day. Planets here are read as shaping how you work and how you look after yourself: Mars here can be tireless, Neptune can blur routines, Saturn can bring discipline or overwork. It is naturally linked with Virgo and Mercury.
The seventh house: partners and close relationships
The 7th house begins at the Descendant, opposite the Ascendant. It covers marriage and committed partnerships, business partners, open rivals and every one-to-one relationship. It describes what you look for in others. On an astrocartography map, the DSC lines mark the places where a planet sits right on this cusp. It is naturally linked with Libra and Venus.
The eighth house: intimacy, shared resources and transformation
The 8th house covers what you share and merge with others: joint finances, debts, inheritance, sexuality and deep emotional bonds, along with endings and renewal. It is naturally linked with Scorpio, and with Pluto and traditionally Mars.
The ninth house: travel, study, beliefs and publishing
The 9th house covers the long view: higher education, philosophy and faith, foreign travel and other cultures, law and publishing. It is naturally linked with Sagittarius and Jupiter.
The tenth house: career, reputation and public life
The 10th house begins at the Midheaven, the highest point of the chart. It covers career, ambition, status and reputation: what you are known for. It is naturally linked with Capricorn and Saturn, and on an astrocartography map the MC lines mark the places where a planet sits right on this cusp.
The eleventh house: friends, groups and hopes
The 11th house covers friendship, networks, communities and causes, and your hopes for the future. It is naturally linked with Aquarius, and with Uranus and traditionally Saturn.
The twelfth house: solitude, rest and retreat
The 12th house, just above the Ascendant, covers what is hidden or behind the scenes: rest, solitude, dreams, the unconscious, and places set apart from daily life, such as hospitals and other institutions. It is read as a house of endings, compassion and inner work. It is naturally linked with Pisces, and with Neptune and traditionally Jupiter.
Angular, succedent and cadent houses
The houses fall into three groups of four. The angular houses (1st, 4th, 7th and 10th) follow the four angles and are read as the most powerful: planets there act visibly in the world. The succedent houses (2nd, 5th, 8th and 11th) follow them and are read as building and holding resources. The cadent houses (3rd, 6th, 9th and 12th) are read as adapting, learning and preparing for change.
The same logic is behind astrocartography. A planet on one of the four angles at a place is exactly what the map's lines show, which is why a line is read as that planet at full volume.
House systems
Astrologers agree on the angles but divide the space between them in different ways. Placidus, this site's default, divides by time: the hours each degree takes to climb from the horizon to the Midheaven, in thirds. Whole Sign gives each house one complete sign, starting with the rising sign. Equal houses are 30° each from the Ascendant, and Porphyry splits each quarter between the angles into three equal parts. Near the poles, where Placidus breaks down, the calculators switch to Porphyry and say so.
Every system gives the same signs and aspects; only a planet close to a house boundary can change house. The birth chart calculator lets you switch systems and compare.