The city of Bangkok is the capital, largest urban area and primary city of Thailand. Known in Thai as Krung Thep Mahanakhon, it was a small trading post at the mouth of the Chao Phraya River during the Ayutthaya Kingdom. It came to the forefront of Siam when it was given the status as the capital city in 1768 after the burning of Ayutthaya. However, the current Rattanakosin Kingdom did not begin until 1782 when the capital was moved across the river after being sacked by the Burmese. The Rattanakosin capital is now more formally called "Phra Nakhon" (Thai: พระนคร), pertaining to the ancient boundaries in the metropolis' core and the name Bangkok now incorporates the urban build-up since the 18th century which has its own public administration and governor.

In the span of over two hundred years, Bangkok has grown to become the political, social and economic center of not only Thailand but for Indochina and South East Asia. Its influence in the arts, politics, fashion, education and entertainment as well as being a business, financial and cultural center of Asia has given Bangkok the status of a global city.

Bangkok is the world's 22nd largest city by population with approximately 8,160,522 registered residents (July 2007). However, similar to most regional centers, due to large unregistered permanent migrants from the North East of Thailand and other Asian nations in combination with those who commute to Bangkok during the day for work, the population of greater Bangkok is estimated to be closer to 15 million people. This has in turn shifted the country from being a rather homogeneous Thai population to an increasingly vibrant mix of Western, Indian and Chinese people, in doing so, giving the city a cosmopolitan status. The capital is part of the heavily urbanized triangle of central and eastern Thailand which stretches from Nakhon Ratchasima along Bangkok to the industrialized eastern seaboardit is the most built-up area mainland-South East Asia.

The Bangkok Province borders six other provinces: Nonthaburi, Pathum Thani, Samut Prakan, Samut Sakhon and Nakhon Pathom, and all five provinces are joined in the conurbation of the Bangkok Metropolitan Area.