Obtaining a Visa is mandatory to travel to India.
As a tourist, you may ask for a 3 months, 6 months or 1 year Visa.
From France, Visa requests may be done through a specialized agency, if you lack the time to go yourself, or directly at the India Visa Center in Paris 10th.
A common mistake when filling out the
web form is forgetting to note down the Request Ident. The ident is necessary to review the form and print it... If you lose the Ident number, as I did, the only solution is to call them during the week, you are asked a few questions to assert your identity and finally given the Ident number.
In the Visa Center, be sure to bring all the papers requested in the Web Site along with your passport. Express care takes a single day for an extra price, or you can wait one week for the usual care, and come back when the Visa has been accepted.
Queuing was decent when I was there (half an hour). Cost for the Visa was 50 Euro (assuming no Express care and going there yourself).