The official language of Bihar is Hindi. It is the most widely spoken language in the state, with over 80% of the population speaking it as their first language. Hindi is also the official language of India, and is used in government, education, and the media.
Bhojpuri is another major language spoken in Bihar. It is a dialect of Hindi, and is spoken by about 20% of the population. Bhojpuri is also spoken in the neighboring states of Uttar Pradesh, Jharkhand, and West Bengal.
Maithili is another major language spoken in Bihar. It is a separate language from Hindi, and is spoken by about 10% of the population. Maithili is also spoken in the neighboring states of Nepal and Jharkhand.
Magahi is a minor language spoken in Bihar. It is a dialect of Hindi, and is spoken by about 5% of the population. Magahi is also spoken in the neighboring state of Jharkhand.
In conclusion, the official language of Bihar is Hindi. It is the most widely spoken language in the state, with over 80% of the population speaking it as their first language. Hindi is also the official language of India, and is used in government, education, and the media.