Mega Manila is the term used for the regions of Central Luzon, CALABARZON, MIMAROPA and Metro Manila. It is frequently used in the press, advertising, television and radio. The significance is that the National Capital Region aka Metro Manila does not bound the urban/suburban sprawl of Manila. In addition, some suburbs outside of Metro Manila have densities exceeding cities inside Metro Manila.

The concept of Mega Manila, also somewhat corresponds to Greater Manila, was originally an attempt by the former Governor of Metro Manila Imelda Marcos, which she wanted to expand Metro Manila into the Philippine Sea with Quezon as its final jurisdiction. There are multiple definitions.

Mega Manila, as a loose metropolitan definition defined by the Philippine Information Agency (PIA), is further 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 km. Of course, this definition includes many rural areas.

Manila (English: /məˈnɪlə/; Tagalog: Maynila, [majˈnilaʔ]) is the capital of the Philippines. It is one of the sixteen cities (along with the smaller municipality of Pateros) that comprise Metro Manila.

Manila is located on the eastern shore of Manila Bay and is bordered by Navotas and Caloocan to the north; Quezon City to the northeast; San Juan and Mandaluyong to the east; Makati to the southeast, and Pasay to the south.

Manila has a total population of more than 1,652,171 according to the 2010 census. Manila is the second most populous city in the Philippines, behind its neighbor, Quezon City. The populace inhabit an area of only 38.55 square kilometers, making Manila the most densely populated city in the world.Metro Manila is the most populous metropolitan area in the Philippines and the 11th in the world with an estimated population of 16,300,000. The greater urban area is the fifth-most populous in the world and has an estimated metropolitan population of 20,654,307 people.

The city is divided into six legislative districts and consists of sixteen geographical districts: Binondo, Ermita, Intramuros, Malate, Paco, Pandacan, Port Area, Quiapo, Sampaloc, San Andres, San Miguel, San Nicolas, Santa Ana, Santa Cruz, Santa Mesa and Tondo. Bustling commerce and some of the most historically and culturally significant iconic landmarks in the country, as well as the seat of the executive and judicial branches of the government are to be found in the city; and it is also home to many scientific and educational institutions, numerous sport facilities, a variety of other culturally and historically significant venues. As a primary transportation hub and with the larger capital region bearing its name, there is very little of a general nature to be found in cities anywhere that Manila is lacking.