Langar (Sikhism)

In Sikhism, a langar (, 'kitchen') is the community kitchen of a gurdwara, which will serve meals to all free of charge and does not make a distinction of religion, caste, gender, economic status or ethnicity. People sit on the floor and eat together, and the kitchen is maintained and serviced by Sikh community volunteers. The meals served at a langar are always vegetarian.
Etymology.
"Langar" is a Persian word and came into Punjabi from it.
Origins.
As per Sikh historian Gurinder Singh Mann, free food distribution practices were already in vogue in fifteenth century among various religious groups like Hindu Nath Yogis and Muslim Sufi saints.
According to Arvind-Pal Singh Mandair, a professor of Sikh studies, community kitchens were already operating in Punjab when Guru Nanak founded Sikhism, and these were run by Gorakhnath orders and Muslim Sufi groups.
The roots of such community kitchen and volunteer-run charitable feeding is very old in Indian tradition; for example: Hindu temples of the Gupta Empire era had attached kitchen and almshouse called "dharma-shala" or "dharma-sattra" to feed the travelers and poor for free, or whatever donation they may leave. These community kitchens and rest houses are evidenced in epigraphical evidence, and in some cases referred to as "satram" (for example, "Annasya Satram"), "choultry", or "chathram" in parts of India. In fact, Sikh historian Kapur Singh refers Langar as an Aryan institution.
The Chinese Buddhist pilgrim I Ching (7th century CE) wrote about monasteries with such volunteer-run kitchens. The institution of the Langar emerged from Fariduddin Ganjshakar, a Sufi Muslim saint living in the Punjab region during the 13th century. This concept further spread and is documented in "Jawahir al-Faridi" compiled in 1623 CE. 
The concept of langar—which was designed to be upheld among all people, regardless of religion, caste, colour, creed, age, gender, or social status—was an innovative charity and symbol of equality introduced into Sikhism by its founder, Guru Nanak around 1500 CE in North Indian state of Punjab.
The second Guru of Sikhism, Guru Angad, is remembered in Sikh tradition for systematizing the institution of langar in all Sikh temple premises, where visitors from near and far could get a free simple meal in a simple and equal seating. He also set rules and training method for volunteers ("sevadars") who operated the kitchen, placing emphasis on treating it as a place of rest and refuge, and being always polite and hospitable to all visitors.
It was the third Guru, Guru Amar Das, who established langar as a prominent institution, and required people to dine together irrespective of their caste and class. He encouraged the practice of langar, and made all those who visited him attend langar before they could speak to him.
Contemporary practice.
Langar is a practice which promotes the idea of equality. People sit together on the floor as equals with no discrimination of class, race or income to have a vegetarian meal served by volunteers. Anyone can volunteer in langar, regardless of whether or not they are Sikh adherents.
Langars are held in gurdwaras all over the world, most of which attract homeless population. The volunteers feed them without any discrimination, along with the other devotees who gather. Almost all gurdwaras operate langars where local communities, sometimes consisting of hundreds or thousands of visitors, join together for a simple vegetarian meal.