Religion
Buddhism: 95 percent (Theravada Buddhism).
The rest are Muslim or so.
About Thai Buddhism:
Different in Japan, Buddhism in Thailand is "Theravada".
(Buddhism in Japan is "Mahayana".)
("Theravada" is also called "Hinayana" (Lesser Vehicle) against "Mahayana" (Greater Vehicle), but this is inaccurate or disparaging term. Trying to define superiority or inferiority is funny.)
This Buddhism was spread from India to southeast Asia such as Cambodia, Laos and Myanmar including Thailand, and the purpose is the emancipation of the individual by own efforts. It is believed that ordinary people can earn merit by giving something as charity or doing good things to monks or temples and can be happy. This means that the one who is thankful is not monks but ordinary people.
(Monks until 20 years old have 10 religious precepts, and monks at the age of 21 years old or more have 227 religious precepts.)
Buddhism is really sacred
Buddhism is really sacred for Thai people.
When you visit temples, they might not accept to enter if you don't care about clothes, like if you wear clothes with showing a lot of your skin such as shorts and sleeveless shirts. Correct behavior and proper clothes are necessary when visiting temples in Thailand.