Title: Languages of Thailand
Content:  Thailand is home to 71 living languages, with the majority of people speaking languages of the Southwestern Tai family, and the national language being Thai. Lao is spoken along the borders with the Laos PDR, Karen languages are spoken along the border with Myanmar, Khmer is spoken near Cambodia and Malay is spoken in the south near Malaysia. Sixty-two 'domestic' languages are officially recognized, and international languages spoken in Thailand, primarily by international workers, expatriates and business people, include Burmese, Karen, English, Chinese, Japanese, and Vietnamese, among others.
Title: Thai language
Content:  Thai, or Central Thai (historically Siamese; ภาษาไทย), is a Tai language of the Kra–Dai language family spoken by the Central Thai people and a vast majority of Thai Chinese. It is the sole official language of Thailand. Thai is the most spoken of over 60 languages of Thailand by both number of native and overall speakers. Over half of its vocabulary is derived from or borrowed from Pali, Sanskrit, Mon and Old Khmer. It is a tonal and analytic language, similar to Chinese and Vietnamese. Thai has a complex orthography and system of relational markers. Spoken Thai, depending on standard sociolinguistic factors such as age, gender, class, spatial proximity, and the urban/rural divide, is partly mutually intelligible with Lao, Isan, and some fellow Southwestern Tai languages. These languages are written with slightly different scripts but are linguistically similar and effectively form a dialect continuum. As a dominant language in all aspects of society in Thailand, Thai initially saw gradual and later widespread adoption as a second language among the country's minority ethnic groups since the establishment of the Rattanakosin Kingdom in late 18th century. Ethnic minorities today are predominantly bilingual, speaking Thai alongside their native language or dialect.
Title: Thai language
Content:  According to Ethnologue, Thai language is spoken by over 20 million people (2000). Moreover, most Thais in the northern and the northeastern (Isaan) parts of the country today are bilingual speakers of Central Thai and their respective regional dialects due to the fact that (Central) Thai is the language of television, education, news reporting, and all forms of media. A recent research found that the speakers of the Northern Thai language (or Kham Mueang) have become so few, as most people in northern Thailand now invariably speak Standard Thai, so that they are now using mostly Central Thai words and seasoning their speech only with "kham mueang" accent. Standard Thai is based on the register of the educated classes in Bangkok. In addition to Central Thai, Thailand is home to other related Tai languages. Although some linguists classify these dialects as related but distinct languages, native speakers often identify them as regional variants or dialects of the "same" Thai language, or as "different kinds of Thai".
Title: List of lingua francas
Content:  Much of Thailand does not speak Thai proper as their first language and instead speaks a closely related language, such as Isan, Lanna, or Southern Thai; nevertheless, citizens use the Thai of Central Thailand to communicate with one another.
Title: Languages of Thailand
Content:  Two major dialects of Thais, the national language, are spoken in Thailand: Central Thai and Southern Thai. Northern Thai is spoken in the northern provinces that were formerly part of the independent kingdom of Lan Na while Isan, a Lao dialect, is the native language of the northeast. Both languages are limited mutually intelligible with Central Thai, with the degree depending on standard sociolinguistic factors. The sole official language of Thailand is Central Thai (Siamese), a native language in Central (including the Bangkok Metropolitan Region), Southwestern, Eastern Thailand and Chinese major cities outside Siamese sphere such as Hatyai, Bandon, Nangrong, Mueang Khonkaen etc. 
Title: Demographics of Thailand
Content:  Thailand is dominated by languages of the Southwestern Tai family. Karen languages are spoken along the border with Burma, Khmer is spoken near Cambodia (and previously throughout central Thailand), and Malay in the south near Malaysia. The Thai hill tribes speak numerous small languages, many Chinese retain varieties of Chinese, and there are half a dozen sign languages. Thailand has 73 living languages. The following table shows first languages in Thailand with 400,000 or more speakers according to the Royal Thai Government's 2011 Country Report to the Committee Responsible for the International Convention on the Elimination of All Forms of Racial Discrimination. The following table employs 2000 census data. Caution should be exercised with Thai census 
Title: Thai people
Content:  Thai people (ชาวไทย; endonym), Central/Southern Thai people (คนภาคกลาง, ; Thai of Chinese origin's exonym) or Siamese (ชาวสยาม; historically and sometimes domestically), in a narrow sense, are a Tai ethnic group dominant in Central and Southern Thailand (Siam proper). Part of the larger Tai ethno-linguistic group native to Southeast Asia as well as Southern China and Northeast India, Thais speak the Central Thai language, which is classified as part of the Kra–Dai family of languages. The majority of Thais are followers of Theravada Buddhism. As a result of government policy during the 1930s and 1940s resulting in successful forced assimilation of many the various ethno-linguistic groups in the country into the dominant Thai language and culture, the term Thai people has come to refer to the population of Thailand in general. This includes other subgroups of the Tai ethno-linguistic group, such as the Yuan people and the Isan people, as well as non-Tai groups, the largest of which is that of the ethnic Chinese.
Title: Thailand
Content:  The official language of Thailand is Thai, a Kra–Dai language closely related to Lao, Shan in Myanmar, and numerous smaller languages spoken in an arc from Hainan and Yunnan south to the Chinese border. It is the principal language of education and government and spoken throughout the country. The standard is based on the dialect of the central Thai people, and it is written in the Thai alphabet, an abugida script that evolved from the Khmer alphabet. Sixty-two languages were recognised by the Royal Thai Government. For the purposes of the national census, four dialects of Thai exist; these partly coincide with regional designations, such as Southern Thai and Northern Thai. The largest of Thailand's minority languages is the Lao dialect of Isan spoken in 
Title: Outline of Thailand
Content:  world. Tai groups & people who speak Tai are the majority population in Thailand, with Tai-Lao speakers making up 25% of the population. The heartland of Thailand is the Chao Phraya River Valley, where the original inhabitants were Mon-speaking people. The Mon people are now a minority and the Mon language endangered. The valley later gained control over Eastern Thailand as well, known as the Korat Plateau. This area is not mountainous, as its name would suggest. Although the people of this area have largely adopted Thai culture, there is still a mixture of many Tai-Kadai, Khmer, and Cambodian speakers. Northern Thailand is mountainous and holds many minority groups: "hill tribes." Another mountainous region is the Malay Peninsula, where the 3rd largest population of Malay people live. Many in this area speak Mon-related languages.
Title: Languages of Thailand
Content:  Thai is a Kra-Dai language closely related to Lao, Shan, and numerous indigenous languages of southern China and northern Vietnam. It is the principal language of education and government and is spoken throughout the country. The standard is written in the Thai alphabet, an abugida that evolved from the Khmer script. Although Isan languages of Northern Thai and, to a lesser extent, Southern Thai languages have limited mutual intelligibility with one another and is classified as a separate language by most linguists, the Thai government has historically treated them as dialects of one "Thai language" for political reasons of Thai national identity building.

Question: what language do people from thailand speak?
Answer: Mon Language.