Isan language
Isan is the name for a number of closely related dialects which are spoken in the Northeast of Thailand and neighbouring countries. Isan is mostly used for informal  communication. Isan consists of a number of dialects, there is no official language. People who speak one dialect usually understand the others. When Isan is written down, the Thai alphabet is used most of the time. Very rarely, the Lao alphabet, which is also used to write the Laotian language is used. About 20 million people speak the Isan language as their first language. About a third of the population of Thailand, and 80% of the speakers of Laotian understand it.