The Sikh religion promotes kindness, generosity, and selflessness, and this is highlighted at the gurdwara, the Sikh's place of worship, where free meals are served to everyone, regardless of religion, gender, race, or class, promoting the principles of equality.
Langar is a Sikh term for the kitchen/canteen in a gurdwara where food is served for free. Only vegetarian food is served so that everyone can be catered for.
The preparation and cooking of the food is shared by everyone as a display of sewa - the selfless service to others in the community.
The langar was established because Guru Nanak Dev Ji, the first Guru of the Sikhs, disagreed with the similar Hindu system where people of different classes do not eat together.