Bangkok, officially known in Thai as Krung Thep Maha Nakhon and colloquially as Krung Thep, is the capital and most populous city of Thailand. The city occupies 1,568.7 square kilometres (605.7 sq mi) in the Chao Phraya River delta in central Thailand and has an estimated population of 11.4 million people as of 2024, 15.9% of the country's population. Over 17.4 million people (25% of Thailand's population) live within the surrounding Bangkok Metropolitan Region as of the 2021 estimate, making Bangkok a megacity and an extreme primate city, dwarfing Thailand's other urban centres in both size and importance to the national economy.
Bangkok traces its roots to a small trading post during the Ayutthaya era in the 15th century, which eventually grew and became the site of two capital cities, Thonburi in 1767 and Rattanakosin in 1782. Bangkok was at the heart of the modernization of Siam during the late 19th century, as the country faced pressures from the West. The city was at the centre of the country's political struggles throughout the 20th century, as Siamâlater renamed Thailandâabolished absolute monarchy, adopted constitutional rule, and underwent numerous coups and several uprisings. The city, incorporated as a special administrative area under the Bangkok Metropolitan Administration in 1972, grew rapidly during the 1960s through the 1980s and now exerts a significant impact on Thailand's politics, economy, education, media, and modern society.