Passport
You must have a passport with you all the time. It's the most basic travel document. Also ensure that your passport will be valid for the entire period you intend to remain overseas, if your passport is lost or stolen, immediately contact your country's embassy or consulate in Delhi and also to nearest police station.

Apply for Passport
The best time to apply for a passport or to renew is during the fall and winter. Before any trip, be sure to check your passport's expiration date and, if necessary, renew it as soon as possible.

Visa
You need a visa to visit India. But if you are coming from Nepal you only need Identification, and visa is issued at the airport only. Note that with a three month visa, your entry to India must be within 30 day's from the date of issue of the visa. Also, the six month visa is valid from the date of issue of the visa, not the date you enter India five month after the visa was issued, it will be valid only for one month not the full six month. If you enter India the day after it was issued, you can stay for the full six month.