Wikipedia
The Principalía or noble class was the ruling and usually educated upper class in the towns of Spanish Philippines, comprising the gobernadorcillo (who had functions similar to a town mayor), and the cabezas de barangay (heads of the barangays) who governed the districts. The distinction or status of being part of the principalía was a hereditary right. However, it could also be acquired, as attested by the royal decree of (signed in the name of Queen Isabella II by the Minister of the Colonies, José de la Concha).
This distinguished upper class was exempted from tribute (tax) to the Spanish crown during the colonial period. It was the true aristocracy and the true nobility of colonial Philippines, which could be roughly comparable to the patrician class of ancient Rome. The principales (members of the principalía) traced their origin from the precolonial royal and noble class of Datu of the established kingdoms, rajahnates, confederacies, and principalities, as well as the lordships of the smaller ancient social units called barangays in Visayas, Luzon, and Mindanao. The members of this class enjoyed exclusive privileges: only the members of the principalía were allowed to vote, be elected to public office, and be addressed by the title: Don or Doña.
For the most part, the social privileges of the nobles were freely acknowledged as befitting their greater social responsibilities. The gobernadorcillo during that period received a nominal salary and was not provided government funds for public services. In fact more often the gobernadorcillo had to maintain government of his municipality by looking after the post office and the jailhouse, and by managing public infrastructure.
Principales also provided assistance to parishes by helping in the construction of church buildings, and in the pastoral and religious activities of the priests who, being usually among the few Spaniards in most colonial towns, had success in winning the goodwill of the natives. More often, the clergy were the sole representatives of Spain in many parts of the archipelago. Under the Patronato Real of the Spanish crown, these Spanish churchmen were also the king's effective ambassadors, and promoters of the realm.
With the end of Spanish sovereignty over the Philippines after the Spanish–American War in 1898 and the introduction of a democratic, republican system during the American Occupation, the Principalía and their descendants lost their legal authority and social privileges. Many were, however, able to integrate into the new socio-political structure, retaining some degree of influence and power.