Holi is the festival of colours ,Holi is the festival with cultural rituals .the celebration of holi is mention in the puranas as wellas it also menstioned in the 7th century sanskrit drama Rantivali.
there is symbolic legand to express why Holi is celebrated as the festival of colors .
the king Hiranyakashipu was king of multan. prahlad was the son the king.he devoted  the lord vishnu.but the kind did not want that his son devoted the lord vishnu instead of him.so we wanted to punish his son.so he called her sister named HOLIKA.and she tricked him into sitting in pyre Holika weared an immune cloak while prahalad was not.but prahlad recited the name of lard vishnu and at the ebd holika burried but prahlad was safe ,seeing this ,the king did not able tom control his anger,he smashed a piller wish his mace .then lord Narshimha appeared and killed the king Hiranayakashipu .this story show the victory of good over bad or evils ,people applied ash of Holika dahan on their forhead.eventually ,colour powder came to be used to celebrate HOLI