Visa on Arrival
Citizens from over 100 countries, from Albania to Zimbabwe, can apply for a 60-day, double-entry e-Tourist visa online at indianvisaonline.gov.in a minimum of four and a maximum of 120 days before they are due to travel. The fee is US$80 for most nationalities and it's necessary to upload a photograph as well as a copy of your passport, have at least six month's validity in your passport and at least two pages blank. The facility is available at 26 airports, including Delhi, Jaipur, Mumbai, Bengaluru (Bangalore), Chennai, Kochi (Cochin), Goa, Hyderabad, Kolkata and Thiruvanathapuram (Trivandrum) airports, though you can exit through any airport. You should also have a return or onward ticket, though proof of this is not usually requested. If your application is approved, you will receive an attachment to an email, which you'll need to print out and take with you to the airport. You'll then have the e-Tourist visa stamped into your passport at the airport, hence the term 'Visa on Arrival', though you need to apply for it beforehand. It is valid from the date of arrival.
Travellers have reported being asked for documentation showing their hotel confirmation at the airport, though this is not specified on the VOA website.