The three qualities of houses:
Houses are divided (based on their qualities) into 3 groups: Kendra (angular), Panapara (succedent), Apoclima (cadent). Planets in Kendra houses are strongest and active to manifest their potential. Order of strength (starting from strongest): 10, 7, 4, 1. Planets in tenth can dominate chart and even overpower the Udaya Lagna (Ascendant).
These houses are similar in qualities to movable signs. They are called "Lakshmi houses" (goddess of fortune): 1, - fortune of body; 4, - fortune of home; 7, - fortune of marriage; 10, - fortune of career. Planets in Panapara ( succedent) houses are moderate in strength and similar to a fixed singes. Order in decrement of strength: 5, 11, 2, 8. Those houses are generally related to accumulation and maintaining.
They govern income and mind (in sense of self-expression): 5, - intelligence and gain through speculation; 11, - expression of ideas to others and income; 2, - speech and gaining through personal effort; 8, - insight and acquisition through inheritance. Apoclima (Cadent) houses are weakest and correspond to a mutable signs. Order in decrement of strength: 9, 3, 6, 12. Those houses give flexibility and adaptability, but signify some instability, which can bring problems. They can bring spiritual progress. There are also sets of Trikona, Upacharya, Apacharya, Dushtana houses, which will be discussed below. There is also classification of houses according 4 Vedic goals of human life: moksha, - 4, 8, 12; dharma, - 1, 5, 9; artha, - 2, 6,10; kama, - 3, 7, 11. Houses can be related to elements, like signs: agni (fire), - 1, 5, 9 (Aries, Leo, Sagittarius); prithvi (earth), - 2, 6, 10 (Taurus, Virgo, Capricorn); vayu (air), - 3, 7, 11 (Gemini, Libra, Aquarius); apas (water), - 4, 8, 12 (Cancer, Scorpio, Pisces). Last classification is a secondary factor.
Houses 3, 6, 10, 11 are Upachaya (increasing) houses. Planets located in them grow in strength and give progressively better results, as one gets older. Natural malefics do well in these houses and give power to overcome difficulties. The lords Upachaya houses (except 10) usually inauspicious and can cause harm. They are too impulsive in nature. Houses 10 and 11 are best among Upachaya houses.
Houses 1, 2, 4, 7, 8 are Apachaya (decreasing) houses. Planets located in them lose their strength through time. Natural malefics do not do well in these houses. The 8 house is the worst and the most unfortunate house in chart.
Trine (Trikona) houses:
Houses 1, 5, 9 are Trikona (trine) houses. Residency in this set of houses is a source of strength, though kendra placements are a little stronger then Trikona. These houses are houses of Vishnu, deva of dharma. The ninth house is the best in this set, followed by fifth.
Duhsthanas or Difficult Houses:
Houses 12, 8, 6 and according some authors 1 are Duhsthanas (difficult) houses. Those points are difficalt because they are point of transition 8, 6 on both side of descendant and 12 just above ascendant. They are associated with suffering and fear of loss. On the other side houses 12 and 8 are moksha houses and can signify spiritual growth though loss and detachment. Planets located in them, particularly benefics, are weakened and cause problems.
houses of the four goals of life:
Houses 1, 5, 9, - houses of dharma; 2, 6, 10, - artha; 3, 7, 11, - kama and houses 4, 8, 12 are houses of moksha.
houses related to the four elements:
Houses can be related to elements, like signs: agni (fire), - 1, 5, 9 (Aries, Leo, Sagittarius); prithvi (earth), - 2, 6, 10 (Taurus, Virgo, Capricorn); vayu (air), - 3, 7, 11 (Gemini, Libra, Aquarius); apas (water), - 4, 8, 12 (Cancer, Scorpio, Pisces).