Aupasana is a yajna performed daily by Hindus who have been initiated during marriage.
Hindu marriage is conducted with offerings made in the fire.
Aupasana, which must be performed every day, is commenced in this fire and it must be preserved throughout one's life.
The seven pakayajnas (see: Shrauta), rites including upanayana and shraaddha, must be conducted in the aupasana fire.
All rites in which the aupasana fire is used and pertain to an individual and his family are "Grhyakarmas".