Entry

AIR: All the four major cities- New Delhi, Mumbai, Calcutta and Chennai have direct international air connections. Domestic airlines operate between cities. And, the domestic carrier, Indian Airlines, flies into the neighbouring countries.
SEA: Mumbai, which used to be the main point of entry into India, still receives sea travellers via passenger ships and freighters.
ROAD: Overland, there are several points of entry into India. For up-to-date information on border crossing-points, contact Indian overseas missions or government tourist information offices.  

Immigration

All visitors, except those from Nepal and Bhutan, must have valid passports stamped with current visas. Visitors must register with the Foreigners’ Regional Registration Office within 14 days of arrival. Your hotel will take care of this service upon check-in. In any case, contact the nearest Indian embassy or consulate in your home country before making your travel plans.
All Indian consular offices around the world issue visas. Business travellers should apply for a multiple-entry business visa, which is valid for one year. Special visas are also issued for trekking, botanical expeditions, and sports and journalism related activities.
Visitors may move freely throughout the country, except to restricted or prohibited areas. 

Customs

Visitors possessing more than US$ 10,000 (or the equivalent in travellers' cheques or bank notes) must fill in a currency declaration form. Visitors may bring in up to 200 cigarettes or 50 cigars, and one litre of alcohol, duty-free. Non-sporting firearms and narcotics are prohibited, as are gold bullion or coins (except by Indian nationals returning from working abroad, who may bring in a maximum of 5 kilograms).
The penalties for violations are heavy. If you plan to bring in your own VCR or portable computer to use while in India, ask for a re-export permit from customs officials when you arrive. The permit will be written into the back of your passport, and unless you can present the item to Customs while leaving, duty will be levied.
If the item has been lost or stolen, make a prompt report to the nearest police station and get a copy of the First Information Report (FIR) taken down by the police. Show this report to the Assistant Collector of Customs, who will then decide whether or not to levy duty.
India restricts the export of antiques, including foreign-made artefacts and items more than 100 years old. The Archaeological Survey of India is the authority that determines whether items are restricted. Visitors may not bring in or take out of India anything made from endangered animal species. 

Currency

The units of Indian currency are the Rupee and Paisa (100 Paisa equal 1 Rupee). Paper money is in denominations of Rupees 1, 2, 5, 10, 20, 50, 100, 500 and 1000. Coins are in denominations of Rupees 1, 2 and 5.
Visitors may not bring in or take out any Indian currency, except in the form of travellers' checks. Do not use unauthorised moneychangers for exchanging foreign currency. You run the risk of receiving forged rupees, or being cheated.
Exchanging facilities are generally available at airports and docks, and authorized moneychangers usually display the rates of exchange. Credit cards are widely accepted in major hotels, restaurants and shops 

Climate

India has three major seasons: winter, summer and the monsoon. The winter months (November to March) are pleasant in most of India, with bright sunny days and cool nights. In the northern plains however, the minimum temperature at times drops steeply.
The Himalayas and its foothills receive snowfall, sometimes till early April. In most parts of western, southern and eastern India, December and January are pleasantly cool but never really chilly.
During the summer months (April-August), northern India is fairly hot, with daytime temperatures around 45 °C. Most hill resorts, like Shimla, Mussourie and Nainital - the summer capitals during the days of the colonial Raj - are busy with Indian tourists beating the heat of their hometowns.
The southwest monsoon usually hits the southern tip of India in early June, and tracks north over the next two months. Most of India receives its major share of rainfall between June and September, the south-eastern areas, in addition, get the north-east monsoon rains between mid-October and the end of December.  

Dress

Light and loose, easily laundered clothing is best for the south, and the northern plains, especially from April to September. You will need warmer clothes, including woollens, for the north during winter. Warm clothing is a must in the hill stations all year round.
India does not have a very formal dress code, though some hotels and clubs could insist on a minimum of formality in their dining rooms - long trousers and a conventional shirt usually suffice.
Businessmen should wear a jacket and tie, or a tailored safari suit when meeting counterparts or senior officials. Women should follow the same principle. When touring, avoid revealing tops, short skirts and all but the baggiest shorts. A set of loose-fitting salwar-kameez is a good investment. 

Language

English is the lingua franca between Indians of different regions. Staff at airline, railway and telecommunication counters and offices are usually fluent in English. Most direction signs usually have an English version too. Books like Words in Indian English by S. Muthiah can help visitors interpret local additions to vocabulary and grammar.
Hindi, the official and most widely spoken language, is concentrated in the northern states. Dravidian languages such as Telugu, Malayalam, Tamil and Kannada prevail in the south.