Bihari Hindi is a form of Hindi mainly spoken in the Bihar

Bihar

Bihar is a state in eastern India. It is the 12th largest state in terms of geographical size at and 3rd largest by population. Almost 58% of Biharis are below the age of 25, which is the highest proportion in India....

 and Jharkhand

Jharkhand

Jharkhand is a state in eastern India. It was carved out of the southern part of Bihar on 15 November 2000. Jharkhand shares its border with the states of Bihar to the north, Uttar Pradesh and Chhattisgarh to the west, Orissa to the south, and West Bengal to the east...

 states of India.

The language deviates slightly from Standard Hindi. The first characteristic is the tone of speaking which is very slow, and many times accompanied by stretching the last word of the sentence. Another important characteristic is gender. In Standard Hindi every non-living thing is given either masculine or feminine gender

Grammatical gender

Grammatical gender is defined linguistically as a system of classes of nouns which trigger specific types of inflections in associated words, such as adjectives, verbs and others. For a system of noun classes to be a gender system, every noun must belong to one of the classes and there should be...

. In Bihari Hindi every non-living object is considered masculine.

Example:- English- Rain is falling. Standard Hindi - Barish ho rahi hai. (barish, or rain, is feminine) Bihari Hindi- Barish ho raha hai. (barish, rain is now masculine). Mainly people don't use the word main(मैं)for word "I" instead word Hum(हम)(We) for word "I" is used. Also people from places like Madhubani and Darbhanga

Darbhanga

Darbhangā is a twin city and a municipal corporation and the capital city of the Darbhanga district and Darbhanga Division in the state of Bihar, India. It is one of the most important districts of North Bihar situated in the very heart of Mithilanchal. According to the latest 2011 census, the...

 talks with too much respect and never uses word Tum(तुम)(you) instead word aap(आप) is used to talk to everyone.
Many people pronounce the letter ड़(ṛa) as र(ra) in many Bihari Hindi words. Also any letter starting with half consonant

Consonant

In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are , pronounced with the lips; , pronounced with the front of the tongue; , pronounced with the back of the tongue; , pronounced in the throat; and ,...

 of Devanagari alphabet

Devanagari

Devanagari |deva]]" and "nāgarī" ), also called Nagari , is an abugida alphabet of India and Nepal...

that is pronounced with a(अ) or e(इ) depending upon words. However, not many but not everyone who speaks like that. ex. gyarah(ग्यारह) (means eleven) sometimes pronounced as egyarah(इग्यारह).
Bihari Hindi has many regional words, such as 'burbak' (fool), 'ka' (what) etc.