What are the functions of those roots of the banyan tree?

A banyan, also spelled "banian",[1] is a fig that begins its life as an epiphyte,[2] i. e. a plant that grows on another plant, when its seed germinates in a crack or crevice of a host tree or human edifice. "Banyan" often specifically denominates Ficus benghalensis (the "Indian banyan"), which is the national tree of the Republic of India,[3] though the name also has been generalized to denominate all figs that share a common life cycle and used systematically in taxonomy to denominate the subgenus Urostigma.[4]Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan trees, the warm-temperate rainforest rātā (Metrosideros robusta) and pōhutukawa (M. excelsa) trees of New Zealand and vines such as Common Ivy (Hedera helix) and poison ivy (Toxicodendron radicans).