Thailand is the world's 51st-largest country in terms of total area, with an area of approximately 513,000 km2, and is the 20th-most-populous country, with around 64 million people. Thailand officially the Kingdom of Thailand formerly known as Siam is a country located at the centre of the Indochina peninsula in Southeast Asia. It is bordered to the north by Burma 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 Burma. Its maritime boundaries include Vietnam in the Gulf of Thailand to the southeast, and Indonesia and India in the Andaman Sea to the southwest.

The king of Thailand is titled Head of State, Head of the Armed Forces, the Upholder of the Buddhist religion, and the Defender of all Faiths.Thailand is home to several distinct geographic regions, partly corresponding to the provincial groups. The north of the country is the mountainous area of the Thai highlands, with the highest point being DoiInthanon in the Thanon Thong Chai Range at 2,565 metres (8,415 ft) above sea level. The northeast, Isan, consists of the Khorat Plateau, bordered to the east by the Mekong River. The centre of the country is dominated by the predominantly flat Chao Phraya river valley, which runs into the Gulf of Thailand.

The local climate is tropical and characterized by monsoons. There is a rainy, warm, and cloudy southwest monsoon from mid-May to September, as well as a dry, cool northeast monsoon from November to mid-March. Thai culture has been shaped by many influences, including Indian, Lao, Burmese, Cambodian, Chinese andthe rest of Southeast Asia. Thailand's national religion Theravada Buddhism is important to modern Thai identity. Thai Buddhism has evolved over time to include many regional beliefs originating from Hinduism, animism as well as ancestor worship.