Lao, sometimes referred to as Laotian (ລາວ, [láːw] 'Lao' or ພາສາລາວ, [pʰáːsǎːláːw] 'Lao language'), is a Kra–Dai language and the language of the ethnic Lao people. It is spoken in Laos, where it is the official language, as well as northeast Thailand, where it is usually referred to as Isan. Lao serves as a lingua franca among all citizens of Laos, who speak approximately 90 other languages, many of which are unrelated to Lao. Modern Lao (language) is heavily influenced by the Thai language. A vast number of technical terms as well as common usage are adopted directly from Thai.
Like other Tai languages, Lao is a tonal language and has a complex system of relational markers.[clarification needed] Spoken Lao is mutually intelligible with Thai and Isan, fellow Southwestern Tai languages, to such a degree that their speakers are able to effectively communicate with one another speaking their respective languages. These languages are written with slightly different scripts but are linguistically similar and effectively form a dialect continuum.
Although there is no official standard, the Vientiane dialect became the de facto standard language in the second-half of the 20th century.
(Courtesy of Laotian Language Wikipedia)