Calabarzon

Calabarzon (officially stylized in all caps; English: /ˌkɑːləbɑːrˈzɒn/; Tagalog: [kalɐbaɾˈsɔn]), sometimes referred to as Southern Tagalog (Tagalog: Timog Katagalugan) and designated as Region IV‑A, is an administrative region in the Philippines. It is situated southeast of Metro Manila and is bordered by Manila Bay and the South China Sea to the west, Lamon Bay and the Bicol Region to the east, Tayabas Bay and the Sibuyan Sea to the south, and Central Luzon to the north. Comprising five provinces—Cavite, Laguna, Batangas, Rizal, and Quezon (hence the acronym)—and one highly urbanized city, Lucena, it is the most populous region in the Philippines, according to the 2020 census (PSA), with over 16.1 million inhabitants. It is also the country's second most densely populated region, after the National Capital Region. Calamba in Laguna serves as the regional center, while Antipolo in Rizal is the most populous city in the region.

Before its creation as a separate region, Calabarzon, along with the Mimaropa region, the province of Aurora, and parts of Metro Manila, comprised the historical region known as Southern Tagalog until they were separated in 2002 through Executive Order No. 103.

The history of the area now known as Calabarzon dates back to early historic times. Local historians believe that three of the 10th century place-names mentioned in the Philippines' earliest known written document, the Laguna Copperplate Inscription, pertain to regions or polities (bayan) along the shores of Laguna de Bay; and some Filipino-Chinese scholars believe the 10th century trading polity known as Ma-i may actually have been the predecessor of the present day town of Bay, Laguna. Since the Spanish colonial period of the Philippines, the region has served as home to some of the most important Philippine historical figures, including the Philippine national hero, José Rizal, who was born in Calamba.