A valid passport and visa are required for travel to India.
All foreign nationals coming to India are required to have a valid passport and a valid Indian Visa. Exceptions are citizens of Bhutan, Nepal and the Maldives. Holders of PIO (Person of Indian Origin) and OCI (Overseas Citizen of India) Cards also only need passports.
The Indian government now offers two options for tourists, a traditional tourist visa or an e-Tourist Visa(eTV) issued electronically.
Now Indian Government is providing Tourist Visa on Arrival enabled by Electronic Authorization (this is called e-Tourist visa).
Please click on following link for more details : (https://indianvisaonline.gov.in/visa/tvoa.html)
Regardless of the duration of the valid visa, the maximum duration of stay in Indiais limited to 6 months (180 days) on each visit. Extension of stay is not granted ontourist visas and it can not be converted into any other visa.