In the course of one’s day to day activities a number of small creatures and insects may be destroyed. In these and other ways, sins may be committed, knowingly or unknowingly. For removing such sins, the scriptures have prescribed five types of Yajnas or worships – Brahma Yajna, Deva Yajna, Pitru Yajna, Manushya Yajna and Bhuta Yajna. Brahma Yajna is the study of sacred books and scriptures. Deva Yajna involves offering worship, bhajans, etc. Pitru Yajna refers to ceremonies to departed ancestors. The fourth one, Manushya Yajna, refers to extending hospitality to guests, invited and uninvited. Bhuta Yajna refers to offering food to animals, birds and insects, and looking after wild animals. By engaging in such service and thereby fulfilling the requirements of these Yajnas, we can atone for sins of various kinds that might have been committed.