All foreign visitors to India must have a valid passport and be in possession of a valid Indian visa. U.S. Citizens are required to secure their visa prior to arrival in India. The government of India has simplified the visa process with their new e-Visa program. Visitors may apply for their visa beginning at 120 days prior to the intended travel date, but not later than 4 days in advance of travel. It is highly recommended to secure your visa well in advance of course. Details may be found on the government’s official e-Visa site found here.
Language
There are 18 officially recognized languages in India, of which Sanskrit and Tamil share a long history of more than 5,000 and 3,000 years respectively. The first official language of the country is Hindi, with English being the second.
Currency
The official currency is the Indian Rupee, with the common symbol INR. One rupee is divided into 100 paise. Common banknotes are 5 rupees, 10 rupees, 20 rupees, 50 rupees, 100 rupees, 500 rupees, and 1,000 rupees. ATM's are found in major cities, and most banks are able to exchange travelers checks, US dollars, and other currencies. Credit cards are widely accepted in all cities, generally for amounts greater than 250 rupees.
Phones & Communications
India's telecommunications network is now the fifth largest in the world, with wireless being the principal growth engine. The international country code for India is 91. Telephone services are available in all major hotels. For mobile phones, check with your telephone provider for international roaming charges in India, and what packages may be available. Internet access is generally available throughout the country. Internet rates at hotels are often pricey, and better rates can be found in the Internet Cafes.
Climate
There are a large number of climatic regions in India, from tropical in the south to alpine in the north. In most parts of India the summer months are Mar-Jun, with Apr-May being the hottest months. Average summer temperatures range from 90F-104F. The rainy season lasts from Jun-Sep, with more rainfall in the south than the north. The upside is lower prices, and less crowded tourist areas. The winter season, or main season, goes from Dec-early Mar, where average temperatures are 50F-59F in the northwest, and 68F-77F in the southeast. The best time to visit the Himalayan region, for example, Ladakh, is from Jun-Sep.
Electricity
The voltage in India is 220V. A converter is required for U.S. appliances rated at 110V. A universal adaptor is also required due to the different plug types.
Time Zone
Despite the size of the country there is a single time zone in India, which is 5.5 hours ahead of GMT, or 10.5 hours ahead of U.S. Eastern Standard Time.
Tipping
It is very customary to tip in India. The local expression is baksheesh, or money for tea or coffee. Tipping is done after services have been rendered, but in certain cases beforehand to insure good and prompt service. Most people in the service industry expect tips, including bellboys, taxi drivers, and railway porters. It's good to have small rupee notes handy, in 5-10 rupee denominations, for such occasions. For drivers and guides who have spent the day with you, more substantial tips, in the range of INR 300, are recommended.
Health
There are no required immunizations to enter India, unless you are arriving from an area affected by yellow fever, in which case proof of vaccination is required. It is strongly recommended that you consult your physician a minimum of four weeks prior to travel to determine if you are up to date on your boosters, and which vaccinations are recommended. Common vaccinations include tetanus, hepatitis A and B, polio, typhoid, varicella, Japanese B Encephalitis, Meningitis, Rabies, and Tuberculosis. It is important to bring along an adequate supply of any essential medication. Most travelers suffer nothing more than tummy problems, so drink only bottled water, avoid street vendor food, and remember that common sense is often the best prevention.