Lares (pl.) (also called Genii loci or, more archaically, Lases) were Roman deities protecting the house and the family.
The Lares are usually depicted as dancing youths, with a horn cup in one hand and a bowl in the other. As progenitors of the family, they were accompanied by symbolic phallic serpents.
Lares are Roman guardian spirits of house and fields. The cult of the Lares is probably derived from the worshipping of the deceased master of the family.
Lares are presumed sons of Hermes and Lara.There are several types of Lares. The most important are the Lares Familiares (guardians of the family), Lares Domestici (guardians of the house), Lares Patrii and Lares Privati. Other guardians were the Lares Permarini (guardians of the sea), Lares Rurales (guardians of the land), Lares Compitales (guardians of crossroads), Lares Viales (guardians of travelers) and Lares Praestitis (guardians of the state).
Over time, their power was extended over houses, country, sea, cities, etc., as the Lares became conflated with other Roman deities and protective spirits such as [[Mani]s, deities of Hades. and Penates.
In contrast to their malignant counterparts the Larvae (Lemures), the Lares are beneficent and friendly spirits. The Genius loci was presumed taking part in all that happened inside the house, and a statue was also put on the table during the meals. It was believed that he blessed the house and brought fertility to the fields.
Lares were deeply venerated by ancient Romans through small statues, usually put in higher places of the house, far from the floor, or even on the roof (but some statues were also on some crossings of roads). Just like the Penates, the Lares were worshipped in small sanctuaries or shrines, called Lararium, which could be found in every Roman house. They were placed in the atrium (the main room) or in the peristylium (a small open court) of the house. Here people sacrificed food to the Lares on holidays.
House spirits in other cultures
Encyclopedia Mythica - by Micha F. Lindemans
Wikipedia - http://en.wikipedia.org