The Thai language uses a phonemic alphabet of 44 consonants and 32 vowels. All syllables must contain a vowel sound, but may begin and/or end with a consonant sound. A syllable which ends in a vowel sound is called open, and a syllable which ends in a consonant is called closed. Each syllable is pronounced in one of five tones: mid, high, low, rising, or falling; as a result, speaking correctly creates pleasing melodic patterns which has led the language to sometimes be called a sing-song language by foreigners. Since the alphabet is phonemic (like English but unlike Chinese), it is possible to pronounce a word without knowing it's meaning.

Most Thai words are a simple single immutable syllable; there are no suffixes, declensions, subject-object agreement, or word conjugations. Thai words are assembled into larger forms by aggregation; perhaps because of this, "Thais greatly appreciate puns and double-entendres which, besides enlivening everyday vernacular, spice and propel outrageous dialogue in popular art forms such as folk theatre." In general, Thai grammar is much simpler than Western languages, as particles and other helper-words are sprinkled about to fine-tune the meaning of a sentence.

Some beginning students are intimidated by the initricacies of language used by people of different social class in Thailand. This is not a problem, however, since the rules are quite general, and foreigners may be allowed more leeway, since the effort to speak Thai is widely appreciated. There are many ways to say "I" or "you," for example, but some are only used by royalty, ecclesiastics, etc., so they won't be of concern to the beginner.

Much like L'Academie Française, there is a governing body for the Thai language, the Royal Institute ราชบัณฑิตยสถาน, which publishes an official Thai dictionary and adds new words to the language as required, possibly drawing on Pali, Sanskrit, Mon, and Khmer, for example.