Calabarzon (/ká-lɑ-bɑr-zon/), formally known as Southern Tagalog Mainland and designated as Region IV-A, is an administrative region in the Philippines. The region comprises five provinces: Cavite, Laguna, Batangas, Rizal, and Quezon; whose names form the acronym CALABARZON. Its regional center is Calamba in Laguna.