The fire ritual (homa)  is one of the important elements in the practice of mantra-yoga, when one tenth of the number of the recited mantra you repeat during the fire ritual, then perform tarpana (abhisheka), marjana and brahmana-bhojana (or kanya-bhojana, if it is shakti-upasana). A homa may include a lot of parts required for realization of a mantra (mantra-siddhis), such as abhisheka and etc., present in the ritual. Here are some photos taken at the ashram of Shri Svamiji Shankarananda, when I performed a havan: