See also: Thai phrasebook

The official language of Thailand is Thai (ภาษาไทย phaasǎa Thai). It is a tonal language, so it can be difficult for native English speakers to learn quickly, but everyone will appreciate any attempt you make. Thai is a language with many dialects, though the Bangkok dialect, also known as Central Thai, is used as the standard and is taught in all schools. Language schools can be found in all larger Thai cities, including Bangkok and Phuket.

Bilingual street sign

In the Muslim-dominated south, dialects of Malay that are largely incomprehensible to speakers of standard Malay/Indonesian are spoken. Unlike in Malaysia, Brunei and Indonesia, the Roman alphabet is not used to write Malay in Thailand, and Thai-Malays uses the Arabic-based Jawi script exclusively to write their language.

Various dialects of Chinese are spoken by the ethnic Chinese community, with Teochew being the dominant dialect in Bangkok's Chinatown. Down south in Hat Yai, Hokkien is also widely understood due to the large number of tourists from Penang. Some people in villages near the Burmese border in the North are descended from Kuomintang refugees from Yunnan and hence, speak the Yunnan dialect of Mandarin. The eastern Isaan dialects are closely related to Lao and there are dozens of small language groups in the tribal areas of the north, some so remote that Thai speakers are few and far between.

Public signage is generally bilingual, written in both Thai and English. There is also some prevalence of Japanese and Chinese signs. Where there is English, it will usually be fairly phonetic - for example "Sawatdee" (meaning hello) is pronounced just as it reads: sa-wat-dee. There is no universal agreement on how to transcribe Thai letters into English, so Khao San Road for example is also commonly spelled Kao Sarn, Kao Sahn, Khao San, Koh Saan, Khaosan, and many other variations. Maps with names in both Thai and English make it easier for locals to try and help you.

Most Thais learn English in school, and most younger upper and middle class Thais, as well as many people working in the service industry in Bangkok and other touristy areas, know enough to "get along" in English. Outside of that, English proficiency is generally poor to non-existent. Most "front desk" people in the travel industry speak at least enough English to communicate, and many are relatively fluent; some also speak one or more other languages popular with their clientèle, such as Chinese, Japanese, German, etc.

Due to the focus on writing and grammar in English classes in the Thai educational system, many Thais often struggle to speak English properly, making them self-conscious about their language skills. The best thing to do is to speak to Thais slowly and shower them with praise as you go along.