Mega Manila is the term used for the megalopolis in the Philippine regions of Central Luzon, Calabarzon, Mimaropa and Metro Manila. It is frequently used in the press, advertising, television, and in radio to refer to provinces bound to Manila. In contrasts with the term Greater Manila Area, which is academically used describe the urbanization process that has long spilled out of Metro Manila's borders, also known as built-up area. Mapping out the built-up area around Manila requires finer granularity than the more generic term Mega Manila allows for. Mega Manila is a general reference to relationship of surrounding provinces to Manila with only reference to provinces, not exact settlement patterns of cities, towns, and barangays—of which may be urban, suburban, mountains, and rural areas that happen to be part of provinces that are close enough to Manila to be lumped into those definitions.
Mega Manila, as a loose metropolitan area defined by the Philippine Information Agency (PIA), is divided into the national capital region (Metro Manila) and the suburbs of regions 3 (Central Luzon) and 4 (Calabarzon and Mimaropa). Mega Manila's 2010 population is projected at 35,607,000, or 37.8% of the country's population, and covers roughly half of Luzon, about 50,000 square kilometers, including many rural areas.
This Nielsen defined area has a higher ownership of televisions per household anywhere in the country due to its relative economic prosperity as compared to other areas in the country. Radio ratings agency Radio Research Council (provided by KBP) also provide measurement of audience ratings.
The stricter Nielsen definition closer reflects the built-up area surrounding Manila than the PIA definition, Yet even the Nielsen definition of Mega Manila cannot be merely equated to the built-up area; the Nielsen definition includes significant undeveloped forested areas, while completely excluding contiguous developed settlements in such places like northern Batangas. Thus the academic definition as used for urban studies for built-up area surrounding Manila requires yet another term (e.g. Greater Manila Area) to disambiguate from the already used terms Mega Manila and Metro Manila.