Planets or Grahas

There are nine planets in vedic astrology out of which seven are actual planets and remaining two are shadow planets rahu and ketu, these are mathematical points also called north and south nodes, may also be imagined as head and tail of a dragon snake. Rahu and ketu are intersecting points of orbits of moon and earth.

Sun - Ravi attributes to soul
Moon - Chandra attributes to mind
Mars - Kuja attributes to strength and action
Mercury - Budha attributes to speech and intellect
Venus - Sukra attributes to potency and creation
Jupiter - Guru attributes to knowledge and prosperity
Saturn - Sani attributes to grief and destruction
North node - Rahu
South node - Ketu

Planets are generally classified into benific(shubha ghrahas) and malefic(paapa ghrahas).

Benefic planets
Jupiter, Venus
Increasing Moon or Shukla paksha
Mercury if unassociated with bad planets

Malefic planets
Sun, Saturn, Mars
Increasing Moon or Krishna paksha
Rahu and Ketu
Mercury if associated with bad planets

Other details of exhaltions and debilitations of planets