CALABARZON is one of the regions of the Philippines. It is designated as Region IV-A and its regional center is Calamba City in Laguna. The region is composed of five provinces, namely: Cavite, Laguna, Batangas, Rizal, and Quezon; whose names form the acronym CALABARZON. The region is also more formally known as Southern Tagalog Mainland.
The region is in southwestern Luzon, just south and east of Metro Manila and is the second most densely populated region. CALABARZON and MIMAROPA were previously combined together as Southern Tagalog, until they were separated in 2002 by virtue of Executive Order No. 103. Executive Order No. 246, dated October 28, 2003, designated Calamba City as the regional center of CALABARZON. The largest city of CALABARZON Region and the second highly-urbanized city is Antipolo City, with Lucena City being the first. CALABARZON is the most populated region in the Philippines, with a population of 12,609,803 inhabitants.