Rai is a title of honour in India and is also used as a surname mainly by Rajput

Rajput

A Rajput is a member of one of the patrilineal clans of western, central, northern India and in some parts of Pakistan. Rajputs are descendants of one of the major ruling warrior classes in the Indian subcontinent, particularly North India...

, Jat of North India

North India

North India, known natively as Uttar Bhārat or Shumālī Hindustān , is a loosely defined region in the northern part of India. The exact meaning of the term varies by usage...

 and Bunts

Bunt (community)

Bunt , previously spelled Bant, are a community of erstwhile nobility, feudatory and gentry from the region of Tulu Nadu in the south west of India which comprises the districts of Udupi and Dakshina Kannada in the Indian state of Karnataka and Kasaragod taluk of Kerala...

 of coastal Karnataka

Karnataka

Karnataka , the land of the Kannadigas, is a state in South West India. It was created on 1 November 1956, with the passing of the States Reorganisation Act and this day is annually celebrated as Karnataka Rajyotsava...

 and Kerala

Kerala

or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....

 in south India.It is also used as a surname by Bhumihar

Bhumihar

Bhumihar or Babhan or Bhuin-har is a Brahmin Hindu community mainly found in the Indian states of Bihar, Jharkhand, Uttar Pradesh and Bundelkhand region of Madhya Pradesh.- Varna status :...

 of 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 Uttar Pradesh

Uttar Pradesh

Uttar Pradesh abbreviation U.P. , is a state located in the northern part of India. With a population of over 200 million people, it is India's most populous state, as well as the world's most populous sub-national entity...

.It is derived from Raja (king, prince or chief) and the Marathi/Telugu variant is Rao, while the Bengalis use Roy/Ray.

Compound titles

Apart from the above-mentioned uses of Rai or combinations for ennobled Hindu court retainers, there also were also titles of honour for Hindus, awarded with a decoration during the British Raj

British Raj

British Raj was the British rule in the Indian subcontinent between 1858 and 1947; The term can also refer to the period of dominion...

 (British colonial rule):

• Rai Bahadur  or Rao Bahadur
  Rao Bahadur
  Rao Bahadur was a title of honour issued in British India to individuals who had performed great service to the nation....
  
  
• Rai Sahib

Sources and references

• RoyalArk Glossary - India
• WorldStatesmen - India

Famous Rai Sahib

• Rai Rajeshwar Bali - 13th Taluqdar of Rampur-Daryabad Estate (Uttar Pradesh)