The most popular one is the RONGALI BIHU or the Bohag Bihu which refers to the onset of the Assamese New Year (April 15 of every year) and the coming of Spring. Its a time of merriment and feasting and continues for several days. The farmers prepare the fields for cultivation of paddy and there is a feeling of joy around. The ladies make pithas and larus (traditional food made of rice and coconut) which gives the real essence of the season. The first day of the bihu is called garu bihu or cow bihu, where the cows are washed and worshipped. This is followed by Manuh (human) bihu. The folk songs associated with the Bohaag Bihu are called Bihugeets or Bihu songs. During this time the young people in the village move around in groups along with pretty girls dressed in the beautiful traditional Assamese attire and singing bihu songs of love and romance. Such gatherings are called Mukoli(open) Bihu or Husuris.
KAATI BIHU or Kongaali Bihu (mid-October) has a different flavour as there is less merriment and the atmosphere has a sense of constrain and solemnity. During this time of the year, the paddy in the fields are in the growing stage and the granaries of the farmers are almost empty. Thus it can be also referred as the empty (kongaali) bihu. The people fast during the day and in the evening offer prayers to the Tulsi plant and also in the paddy fields by lighting a diya (earthen lamp), with the hope that there is a good harvest and also to ward off any evil eyes. There is also exchange of sweets and greetings at this time.
MAGH BIHU or Bhogali Bihu (mid-January) marks the end of harvesting season and there is a lot of feasting and eating during this period. The granaries are full and thus the people come together and make a small hut type structures called MEJIS with the hay of the harvest fields and during the night, prepare food and there is community feasting everywhere. The entire night is spend around a bonfire with people singing bihu songs, beating drums or playing games. The next morning, people gather around the mejis and throw pithas (rice cakes) and betal nuts to it while burning it at the same time. They offer their prayers to the Fire God and mark the end of the harvesting year.