The word langar means literally kitchen. In Sikhism it is often used in the phrase "Gur ka Langar" which refers to the Guru's kitchen. However the true meaning is closer to sacred food service, or divine dining.
History:-
The institution of the Sikh langar, or free kitchen, was started by the first Sikh Guru, Guru Nanak. It was designed to uphold the principle of equality between all people regardless of religion, caste, colour, creed, age, gender or social status, a revolutionary concept in the caste-ordered society of 16th-century India where Sikhism began. In addition to the ideals of equality, the tradition of langar expresses the ethics of sharing, community, inclusiveness and oneness of all humankind. "...the Light of God is in all hearts."
After the Second Sikh Guru, the institution of langar seems to have changed, somewhat, and meat seems to have been excluded from this institution. The reason cited for this by historians is the accommodation of Vaishnavite members of the community
Details:-
Sikhism emphasises community services and helping the needy. One of the distinct features of Sikhism is the common kitchen called Langar.
In every Gurdwara there is a Langar. Every Sikh is supposed to contribute in preparing a communal meal in the free kitchen. The meals are served to all and are eaten sitting on the floor, as this is to emphasize the point that all who are there are equals. Sikhism does not believe in holding fasts, for the body is God's present to the human being; and therefore humans must foster, maintain and preserve it in good, sound condition, unless fasting is done to foster the human.
Every Gurdwara has a Langar attached to it where food is served to anyone without charge. The term Langar is also used for the communal meal served at the Gurdwaras.
The food served in the Langar must be simple, so as to prevent wealthy congregations turning it into a feast that shows off their superiority.
Although Sikhs are not required to be vegetarian, only vegetarian food is served in the Gurdwaras. This ensures that any visitor to the Gurdwara, whatever the dietary restrictions of their faith, can eat in the Langar.
The meal may include chapati (Roti), Dal (pulses), vegetables and rice pudding. Fish and eggs are counted as meat and excluded.