Maithili is an Indo-Aryan language that is spoken by the people of North- Eastern Bihar and Nepal. The language has been named Maithili because it is spoken in the ancient land of Mithila. It is also called Tirhutia because Tirhut is another name of the same region, which is derived from Tirabhukti, which means the bank of the river purified thrice by the sacrifices.

At present, the language has about 30 million speakers in the 26 districts of N.E. Bihar. Moreover it is the second state language of Nepal. The language is spoken by 12% of the total population there. P.E.N (an international organization of letters for Poets, Essayists, Novelists) and the Sahitya Akademi, India have recognized Maithili.

It is the sixteenth most spoken languages in India and the fortieth most spoken languages of the world. It has its own script called the Mithilakshar or Tirhuta, originated from Brahmi, a script of 3 BC also found in Asokan Inscriptions. Present day Maithili writers and public at large have adopted Devanagari script because of its widespread use, popularity and convenience.

People speaking Maithili are 22,000,000 in India (1981) and total in all countries are 24,191,900. Regions where Maithili is spoken are northern Bihar, from Muzaffarpur on the west, past the Kosi on the east to western Purnia District, to the districts of Munger and Bhagalpur in the south, and the Himalayan foothills on the north. It is also spoken in Nepal.

Caste variation more than geographic variation in dialects. Functional intelligibility among all dialects, including those in Nepal. Closest to Magahi. Brahmin and non-Brahmin dialects average 91% lexical similarity.