Horoscope consists of 12 houses or Bhavas. Each house has its own significances in the birth chart, like First house or Lagna is the house of Birth and childhood, where as 12th is the house of Mokhsa or 'Freedom'. 12th house is also the house of loss, which in fact we just lost, because we were born in Lagna. Get it?
Suppose your Lagna is Aries, but if you were born 2 hours before then your lagna would have been Pisces, which now is your 12th house, so you lost that house. Similarly second house is the house of resources, wealth, immediate family that will support first house or yourself to grow and prosper.
Trines - 1, 5 and 9 known as konas, are the most powerful houses in the birth chart.
Angular houses - 1, 4 , 7 and 10 known as Kendras, are foundation pillars for a chart. They are second most powerful house after the Trines or Konas.
Panaparas - The wealth houses, next in strength after the kendras. 2 - Self accumulated wealth, 5 - Wealth through children, 8 - wealth through inheritance or hidden sources and 11 - Gains.
Upchaya - The growth houses, grants one valor, courage and strength to go out and get it. 3 - Initiative, 6 - Effort, 10 - karma and 11 - Gains of fulfillment of Desires.
Dusthana - The dreaded houses are 6, 8 and 12.
Based on one's "aim" or purpose of life, known as Purushartha, the houses are grouped into 4 triangles or trikonas. It is believed that "soul" enters physical body when the planets are in specific alignment with the 4 triangles, making a transient stopover in it's journey to Moksha or Freedom.
Each Triangle has three house, 3 X 4 = 12 house.
First house of the Triangle signifies - Initiative.Middle House signifies - Effort and Focus.
Last house signifies - Accomplishments.
Spiritual Triangle - Known as Dharma Trikona, is the triangle between house associated with element 'Fire'. 1 - Self , 5 - intellect and 9 - Dharma or Purpose. 
Material Triangle - known as Artha Trikona, is the triangle between houses associated with element 'Earth'. 2 - Resources, 6 - Effort and 10 - Karma.
Illusion Triangle - Known as Kama Trikona, is the triangle between houses associated with element 'Air'. 3 - Initiative, 7 Desire and 11 - Gain.
Freedom Triangle - Known as Moksha Trikona, is the triangle between houses associated with element 'Water'. 4 - Comfort, 8 - Transformation and 12 - Moksha.The 12 houses (Bhavas) and their signification -
First House - 'Tanu Bhava' in Sanskrit, the house signifies self, personality,
physical constitution and how the person feels about oneself. How others
rate or consider the individual is analyzed from Arudha lagna; first house is all
about self-image. For analyzing person's mental inclination or
likes/dislikes, fifth house also needs to be taken in account.
BPHS - "Physique, appearance, intellect (or the organ of
intelligence, i.e. brain), complexion of the body, vigor, weakness, happiness,
grief and innate nature are all to be guessed through the ascending Rasi."
It
signifies
ones strengths and weaknesses, physiology, tolerance and adjusting
capabilities. First house and lord's association with different houses
has very profound affect on ones life and personality. The associations
give a combine effect and signify relation of self and outer world.
For example - Among other significations, ninth house also represents father, father figures, superiors and bosses. So any benefic association between ninth and Lagna, be it lordship, placement or nakshatra exchange, will get one support from Bosses and father figures. Similarly relation between sixth and Lagna, unless pacified by unafflicted Jupiter, cascades into court cases, diseases, enemies and self destructive mentality.
In Medical
Astrology, First house signify Head, brain and forehead, and in Ayurveda it denotes bones and Pitta.
First house also signifies Fame, intelligence, appearance, physical comforts along with one's ability to enjoy life. Any relation to the dreaded houses (Dusthanas) is highly undesirable for a comfortable and fortunate life. Benefic positioned in Lagna grant one a pleasing and influential personality.
Second House - 'Dhana Bhava' in Sanskrit, the house signifies immediate family, parental or accumulated wealth, speech, face, right eye, food habits, source of death, acquisition and mother’s elder siblings.
Third House - 'Sahaja Bhava' in Sanskrit, the house signifies younger siblings, courage, subordinates, neighbors, talents, communication, short distance travel, writing skills, publishing, right ear, right hand, respiratory canal and in-laws.
Forth House - 'Bandhu Bhava' in Sanskrit, the house signifies home, mother, motherland, relatives, domestic comforts, landed property, immovable possessions, vehicles, relatives, mental peace, chest, lungs and father’s life in general.
Fifth house – 'Putra Bhava' in Sanskrit, the house signifies children, intellect, creativity, education, mental inclination, Poorva punya (past life merits), speculations, power of logic and spouse of elder siblings.
Sixth House - 'Ari Bhava' in Sanskrit, the house signifies health, illness, diseases, debts, loans, difficulties, disappointments, sorrows, court cases, enemies, oppositions and maternal uncles. Being Upchaya house it also signifies effort and growth.
Seventh House - 'Yuvati Bhava' in Sanskrit, the house signifies partnership, life partner, business partner, marital happiness, reproduction, genitals and related diseases, sex life and death.
Eighth house - 'Randhra Bhava' in Sanskrit, the house is the most dreaded house in Jyotish. The house signifies Longevity, major transformations, catastrophe, death-like experiences, legacies, inheritance, prolonged court cases, unearned wealth, disgrace, degradation, defeat, defame and impediments.
It is the most important house for becoming an astrologer. The house of mystic and psychic abilities, and though infamous, it signifies research, enlightenment, purification, healing and spiritual liberation. It is considered the house of healers.
Ninth House - 'Dharma Bhava' in Sanskrit, the house signifies fortune, prosperity, father, superiors, bosses, spiritual enlightenment, higher education, long distance and foreign travel, lasting fame, philosophy and grand-children.
Tenth house - 'Karma Bhava' in Sanskrit, the house signifies your deeds, profession, professional achievements, government, public administration bodies, legal jurisdiction, financial institutions, public image, social standing, mass dealings, authority, dignity, public reputation, leadership, responsibility, lively hood, duty and principles.
Eleventh House - 'Labha Bhava' in Sanskrit, the house signifies gains, income, money, fulfillment of desires, elder siblings, friends, social-circle, social-image, entertainment, accomplishments and self-growth.
Twelfth House - 'Vyaya Bhava' in Sanskrit, the house signifies expenditure, extravagance, losses, foreign residence, moksha and forced or dreaded confinements such as hospitals, police lock-ups, asylums and jails.
