Thailand, officially the Kingdom of Thailand, formerly known as Siam, is a country at the centre of the Indochinese peninsula in Mainland Southeast Asia. It is bordered to the north by Myanmar and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the west by the Andaman Sea and the southern extremity of Myanmar. Its maritime boundaries include Vietnam in the Gulf of Thailand to the southeast, and Indonesia and India on the Andaman Sea to the southwest.

With an area of 513,120 km², the country is just slightly larger than Spain or slightly more than twice the size of the U.S. state of Wyoming. Until 1939 the country was known as Siam.

By far the largest city is Bangkok, the national capital with estimated 10 million people.

Thailand’s official language is Thai, which uses the Thai alphabet (derived from the Khmer alphabet). There are various dialects of Thai spoken around the country, but the central Thai dialect is the standard.

Minority languages include Isan, Yawi, Chinese dialects, and tribal languages like Mon, Khmer, Viet, and Cham. English is usually taught in school.

Thailand is located in Southeast Asia along the Andaman Sea and Gulf of Thailand.