Almost every north Indian village has its local God or Goddess, set up under a sacred tree and popularly known as Grama Devi or Grama Devata. Local goddesses are often vaguely identified with Durga and are very much part of Hinduism. They maintain an autonomous existence on the fringes of the orthodox pantheon. These deities – mostly depicted as totem and at times not the deities in the traditional sense – could be of any species or form. They may have no connection with any established gods or goddesses. In some cases tales are woven around them to explain their unperceivable potency to protect the villagers. However, there have been certain villages that have an established deity as gramadevata like Bajrang Bali Hanuman or some Mother Goddess, like Shitala or Manasa Devi, notwithstanding their form and nature considerably localized.
The village deities do not normally have any divine lineage. Even a local person of eminence could be deified because of an extraordinary deed to ensure the security of the village. At times the local legends make the village adopt a pre-existing deity.
Generally, the village deities are not worshiped every day. They have their specific days and times marked for worship and this sort of celebration invariably results in the gathering of a small fair at the appointed time.
In routine life no one leaves the village or returns to it without bowing to the gramadevi/devata or raising a slogan in his or her praise or glory. When the groom’s party in a marriage leaves the village or a person goes on an important mission, it is customary to chant the village deity’s name thrice. The ritual is repeated when the whole party or person reaches back safely.
It is believed that invoking the village deity’s name while leaving the village ensures protection to the person’s family and property in his absence and helps him in achieving success. Planting shady trees and having wells dug close to the shrine are some charitable acts of villagers. But nothing of this kind is done in regular fashion.
What is most peculiar in this style of worship is the devotion shown by every villager, irrespective of his or her caste, creed, faith or social status. Evidently local bonds and concerns transcend all other loyalties, prejudices and predilections. For this reason, the village has been deemed as the smallest and self-sufficient unit in the Indian social system and these village deities are honored as custodians of the interests of every villager.
Source - Encyclopedia of Hinduism Volume IV page 356 – 357 IHRF – 2011