Official languages widely used in the Indian territory:

 

Sanskrit - non-regional (It is the primary liturgical language of Hinduism, a philosophical language in Hinduism, Buddhism, and Jainism, and a scholarly literary language that was in use as a lingua franca in the Indian cultural zone. It is also an official language of the state of Uttarakhand )

Hindi 

English

(The Constitution of India designates a bilingual approach for official language of the Government of India employing usage of Hindi written in the Devanagari script, as well as English)

Urdu - non-regional (Urdu and Hindi are nearly identical in basic structure and grammar, and at a colloquial level also in vocabulary and phonology. Urdu is historically associated with the Muslims of the region of Hindustan, spoken my most Indian Muslims and it uses the Arabic script. It is the national language and lingua franca of Pakistan, and an official language of several Indian states)

Sindhi - It is spoken in the states of Rajasthan, Gujarat and Maharashtra. It is also the official language of the Pakistani province of Sindh)

Gujarati - Language of Gujarat and Union Territories of Dadar and Nagar Haveli

Punjabi - The official language of Punjab

Bengali - The state language of West Bengal

Assamese (and Bodo) - Official language of Assam

Dogri (and Urdu) - The language of Jammu and Kashmir

Oriya - The state language of Orissa

Marathi - Language of Maharashtra

Kannada - The official language of Karnataka

Tamil - The state language of Tamil Nadu

Telugu - The official language of Andhra Pradesh

Malayalam - The official language of Kerala

Konkani - The state language of Goa

Manipuri - The official language of Manipur

Khasi - The official language of Meghalaya

Mizo - The official language of Mizoram

Lotha - The official language of Nagaland

Bodo - One of the official languages of Assam (It is a Tibeto-Burman language spoken in north-eastern India and Nepal)

Maithili - It is spoken in Jarkhand and North Bihar of India and South-eastern Nepal 

Dogri - It is spoken in Pakistan and India, chiefly in Jammu and Kashmir, Himachal Pradesh, and also in northern Punjab

Santali - It is spoken in India (mostly in the states of Jharkhand, Assam, Bihar, Orissa, Tripura, and West Bengal), and Bangladesh, Bhutan and Nepal

 

Besides these, there are Indian languages which are spoken by large masses but have still not acquired the status of Scheduled Languages of India. These languages spoken by regional people are known as regional languages of India. This includes Rajasthani, Bihari, Haryanavi, Bhili, Gondi, Tulu among others. Some Indian languages are not widely spoken; they are given the status of minority languages. Mahl and Portuguese languages come under this category.