Own sign, friends and enemies of grahas
An own sign (swarashi) is a sign a graha rules. A planet there is considered comfortable and strong, in the same way that a friend's sign is considered supportive.
What it is
The Sun and Moon each have one own sign: Simha and Karka. Mars has Mesha and Vrishchika, Mercury Mithuna and Kanya, Jupiter Dhanu and Meena, Venus Vrishabha and Tula, and Saturn Makara and Kumbha. Friendship between grahas is a separate table.
How it is worked out or read
An own sign is a dignity that comes from the sign's lord. It is not the same as exaltation, which is a separate and stronger rule for most grahas.
Where it appears on this site
The own signs follow from the lord table in the rashi index. The planetary friendship table is on a separate page.
The ladder of dignity
Classical texts rank a planet's comfort in a sign along a ladder. From strongest to weakest: exaltation, moolatrikona, own sign, the sign of a great friend, a friend's sign, a neutral sign, an enemy's sign, a great enemy's sign, and debilitation. The middle steps use the compound friendship that combines the natural table with the planets' positions in the particular chart. A reader does not need every step for everyday work, but knowing the ladder explains why own sign is strong but not the strongest.
Own sign in practice
A planet in its own sign is described as being at home: it acts with confidence, its significations are well supported and the house it occupies benefits. Mars in Vrishchika, Venus in Tula and Saturn in Kumbha are examples. Because the planet also rules that house, an own-sign placement links the house's themes firmly with the planet's nature. Several yogas, such as the Pancha Mahapurusha yogas, require a planet in its own or exaltation sign in a kendra.
Friends' signs and enemies' signs
A planet in a friend's sign is described as comfortable and helped, much as a guest in a friend's house. In an enemy's sign it is described as uneasy, its results mixed or delayed. These are tendencies rather than verdicts, and they are weighed together with the house, aspects and dashas. The planetary friendship table on this site sets out the relationships needed to place a planet on the ladder.
Own signs as a home base
A planet in its own sign is often described as being at home. The classical texts say it can act without strain and that its results come more readily. Each graha has its own signs: the Sun and Moon one each, and the other five two each, with Rahu and Ketu usually without. Own sign strength is a dignity of the sign's lord, and it is separate from exaltation, which is a relation to a particular sign.
Friends as a second layer
A planet placed in the sign of a friend is read as supported, and a planet in an enemy's sign as strained. The friendship table, covered in its own article, provides the standard relations. The reader combines the planet's own sign, the friendliness of the sign's lord, and the house the planet occupies to form a view. None of these alone decides the reading, and the combination is the classical method.