When you are in a major airport, you will choose between walking the green line or the red line through customs. Green line is for those with nothing to declare, while red-line walkers have declarations to make. Regardless of which line you chose, make sure to have your passport ready, as well as any other documents such as visa paperwork that you will need depending on the length of your stay.
Certain items and goods are not allowed to be imported or exported by tourists. Some of these prohibited items include drugs, pornographic or explicit materials, any materials that infringe on intellectual property rights (such as pirated goods) and certain animal or wildlife products.
Goods that are restricted include guns and ammo, certain animals, plants and vegetables, and in certain cases, precious metals and large amounts of currency.
Personal Duty-Free Allowances
In general, adult tourists who are citizens of the U.S., Canada, Australia or EU countries are entitled to a Duty-Free Allowance of 25,000 Rupees (about $580 U.S.). This personal allowance can't be combined with that of your traveling companions.
Indian Definition of a Tourist
According to the Indian government, a tourist is a person who is not a resident of India, and who has entered India for a planned vacation of less than 6 months in a 12-month window.