The Birth chart is 12 divisions of the Cosmos. There are various types of shapes in which a Birth Chart is casted. Each of the divisions are called Bhava’s. Each of these Bhava’s are of 30 degrees and govern certain aspect of our lives. Planets and signs move into these Bhava’s to give the effects.
The below chart format is practiced in North India
Another dimension of Birth Chart is it controls 4 Ayanas or Goals of life which is Dharma , Artha , Kama , Moksha.
If more planets are in Dharma house , the person will be very dutiful. Shani and Rahu do not promote dharma and hence they will try to destroy dharma if placed in these Bhav’s provided Dharma promoting planets (Surya , Ketu , mangal) fights for the same.
The kendra’s are controlled by Vishnu and Kona’s are Controlled by Laxmi . The 8th Bhav is called as Rudra Bhav which destroy’s everything.