A libation is a ritual pouring of a liquid (ex: milk or other fluid such as corn flour or rice) as an offering to a god or spirit, or in memory of those who have "passed on". It was common in many religions of antiquity and continues to be offered in various cultures today.
Various substances have been used for libations, most commonly wine or olive oil, and in India, ghee. The vessels used in the ritual, including the patera, often had a significant form which differentiated them from secular vessels. The libation could be poured onto something of religious significance, such as an altar, or into the earth.
In East Asia, pouring an offering of rice into a running stream, symbolises the unattachment from karma and bad energy.
Libation was part of ancient Egyptian society where it was a drink offering to honor and please the various divinities, sacred ancestors, humans present and not present, as well as the environment. It is suggested that libation originated somewhere in the upper Nile Valley and spread out to other regions of Africa and the world. According to Ayi Kwei Armah, “[t]his legend explains the rise of a propitiatory custom found everywhere on the African continent: libation, the pouring of alcohol or other drinks as offerings to ancestors and divinities.”
Libations were part of ancient Judaism and are mentioned in the Bible:
And Jacob set up a Pillar in the place where he had spoken with him, a Pillar of Stone; and he poured out a drink offering on it, and poured oil on it.
Isaiah uses libation as a metaphor when describing the end of the Suffering Servant figure who "poured out his life unto death". (53:12)
Libation was a central and vital aspect of ancient Greek religion, and one of the simplest and most common forms of religious practice. It is one of the basic religious acts that define piety in ancient Greece, dating back to the Bronze Age and even prehistoric Greece. Libations were a part of daily life, and the pious might perform them every day in the morning and evening, as well as to begin meals. A libation most often consisted of mixed wine and water, but could also be unmixed wine, honey, oil, water, or milk.