Visitors to India need a tourist visa, which you must obtain in advance.
Visas are not issued on arrival.
Your passport must be valid for at least six months beyond the period of your stay.
The e-Tourist Visa costs around 20 to 80 euros and you can apply for it online.
Important note: The terms for the e-Tourist Visa can be found here: https://indianvisaonline.gov.in/visa/tvoa.html
The visa application itself can be found here: https://indianvisaonline.gov.in/visa/info1.jsp