All foreign nationals need to obtain a visa for visiting India. Conference participants should obtain a "Conference Visa", and accompanying persons should obtain a "Tourist Visa". Persons of Indian origin can use their PIO card instead. There is no "Visa on Arrival" facility.
Typical visa processing time at Indian consulates is 3 working days.
Details for an online application for Indian visa are available at indianvisaonline.gov.in.
You should apply for an Indian visa at least two months prior to your intended travel date. That gives enough time to set things right in case there is a delay for unforeseen reasons.
Chennai (earlier known as Madras) has an international airport, with direct flights to/from Singapore, Kuala Lumpur, Bangkok, Hong Kong, London, Frankfurt, Dubai, Abu Dhabi, Doha, Sharjah, Muscat and Male. Other major international ports of entry into India are Delhi, Mumbai, Bengaluru and Kolkata. Chennai is connected by air, rail and road to all the major cities of India.
International travellers coming to Chennai via Delhi or Mumbai have to change from the international to the domestic airport terminals in these two cities. They should use the free inter-terminal transport available there.
If you are carrying large amount of foreign currency (not travellers cheques but cash), that should be declared at the customs when entering India. Travellers cheques and cards do not have to be declared and are easier to carry. Expensive equipment liable to custom duty (e.g. fancy laptop computers and video cameras) should also be declared at the customs. Such items will be entered in your passport (or a form will be attached to your passport), and you don't have to pay any duty provided that you take them back when you return.
The Indian currency is Rupee (1 US$ = 53.59 Rupees at the beginning of February 2013; more up-to-date information can be found at the Universal Currency Converter). Currency conversion is possible at airports and banks, although many of them deal only with the US-dollar, the Euro and the British-pound. At the end of the trip, rupees can be converted back into foreign currency, but you should keep receipts demonstrating that a larger amount of foreign currency was converted into rupees earlier during the trip.
International credit cards are accepted at many hotels, restaurants and shops, but not everywhere. They can also be used at many ATM's to obtain Indian currency (the logos of acceptable cards are displayed at ATM's), but at an extra cost. The ATM's generally provide a better exchange rate than that offered by hotels and shops. The foreign currency transcation cost will depend on the agreement between you and your credit card company.
Indian currency comes in denominations of Rs.10,20,50,100,500,1000 (as notes) and Rs.0.50,1,2,5,10 (as coins). Avoid accepting currency notes of denominations Rupee 1,2 and 5; ask for the corresponding coins instead. The government has stopped printing these notes, but some old damaged and soiled notes are still in circulation.
- The electricity supply in India is 220 Volts and 50 Hz. Appliances requiring 110 Volts would need a voltage adapter. The electrical sockets require three (or two) round pin plugs, related to the BS 546 standard as described here. Adapters needed for other type of plugs are available in the market.
- Indian local time is ahead of the Greenwich Mean Time (GMT) by 5:30 hours.
- India uses the metric system of measurements (it is after all the birthplace of the decimal system!).
- Vehicles have to obey left hand drive.
- Prepaid mobile telephone cards are easily available. Internet cafes accessible with cash payment are commonplace.