Fiestas are usually held to celebrate the feast day of a patron saint. Thus every town and city in the Philippines has a fiesta of its own. It is part of Filipino culture modified by Spanish influence as early as in the 15th century when the Philippines became a colony of Spain.
The Fiesta is a convenient tool in the Christianization effort of the missionaries, and the subjugation of the people under Spanish rule. It brought people from distant and scattered settlements to town. The town or municipality then became the center of government, worship, commerce, education, and the like. It is the navel of master-subject relationship. It is no wonder the country remained under Spanish rule for nearly nearly four hundred years.
Fiestas are deeply engrained in our culture to this day. In fact every barrio or barangay has a fiesta. So with many sitios or puroks which have their own celebration following the tradition, and for other reasons like anniversaries, significant historical events, or simply a day set for people to get together.