Based on the purpose of the visit, different kind of visas are available such as tourist visa (for 6 months), a business visa (for 6 months, one year or more, multiple entries), or a student visa which can be acquired up to 5 years. A special 10-year visa (US$150, business and tourist) is available to US citizens only. Specialized categories of visas are also available like the missionary visa which is mandatory for anyone who is visiting India primarily to take part in religious activities. Instead of date of entry, an Indian visa is valid from the day it is issued. A minimum two month gap period is must between consecutive tourist visas. Tourist visa valid for 6 months can have maximum duration of stay of 90 days per visit, depending on citizenship. The maximum duration per visit needs to be checked with your local embassy.
These days, many Indian embassies have outsourced visa processing in full or in part to third party companies, so check ahead before going to the embassy.
Depending on the citizenship, rules and validity of visas will differ. So, you must check the website of the Indian embassy, consulate or high commission in your country or contact the local office.
For some countries, even on multiple entry visas, there is supposed to be a two-month gap between leaving India and coming back into the country. These countries are Afghanistan, China, Iran, Pakistan, Iraq, Sudan, Bangladesh, foreigners of Pakistani and Bangladeshi origin, and "stateless persons". The two countries exempted from visas are Nepal and Bhutan.
You need to register within 14 days of your arrival of your whereabouts with the Foreigners Regional Registration Office if you are on a Student, Employment, Research or Missionary visa. You need to register at the local police station if you do not have any fixed place to stay.
You should avoid overstaying a visa as you cannot leave the country until you have paid some hefty fines and presented a large amount of paperwork to either the local immigration office or police station. It may take 3 days or more if weekends, govt. holidays etc. to get the paperwork done.
The visa-on-arrival facility will be available at five more international airports. These cities are Goa, Trivandrum, Bangalore, Hyderabad and Kochi. Earlier, the facility was available at four international airports in Delhi, Mumbai, Kolkata and Chennai. The eleven countries for which the Indian government has permitted Visa-on-Arrival facility are - Japan, Singapore, Finland, Luxembourg, New Zealand, Cambodia, Laos, Vietnam, Philippines, Myanmar and Indonesia.

There are six seasons or ritus that India experiences in a year. These are Vasanta - Spring, Greeshma - Summer, Varsha - Rainy, Sharat - Autumn, Shishira - Winter, Hemanta - "Mild Winter".
India primarily has three main seasons in a year, Summer, Rainy Season (or "Monsoon") and Winter. The Winter season spans the month of December till the beginning of April. The average temperature during this period is approximately 10-15 °C (50-59 °F) in the northwestern parts and close to 20-25 °C (68-77 °F) in the southeastern parts. The Summer months are from April to June. The average temperature during these months is close to 32-40 °C (90-104 °F) in major part of the country. The North experiences some extremes of heat in Summer and cold in Winter, but except in the Himalayan regions, snow is almost unheard of. There is also a brief spring in February and March, especially in North India. In India, it rains only during a specific time of the year which is called the Monsoon season. It lasts from June to September.

In India, you are expected to negotiate the price with street hawkers but not in department stores and the like. If not, you risk overpaying many times, which can be okay if you think that it is cheaper than at home. In most of the big cities and even smaller towns retail chain stores are popping up where the shopping experience is essentially identical to similar stores in the West. There are also some government-run stores like the Cottage Emporium in New Delhi, where you can sample wares from all across the country in air-conditioned comfort. Although you will pay a little more at these stores, you can be sure that what you are getting is not a cheap knockoff. The harder you bargain, the more you save money. A few tries later, you will realise that it is fun.
Often, the more time you spend in a store, the better deals you will get. It is worth spending time getting to know the owner, asking questions, and getting him to show you other products (if you are interested). Once the owner feels that he is making a sufficient profit from you, he will often give you additional goods at a rate close to his cost, rather than the common "foreigner rate". You will get better prices and service by buying many items in one store than by bargaining in multiple stores individually. If you see local people buying in a store, you can probably get the real Indian prices. Ask someone around you quietly, "How much would you pay for this?"
Also, very often you will meet a "friend" in the street inviting you to visit their family's shop. That almost always means that you pay twice as much as when you had been in the shop without your newly found friend.
Baksheesh--small bribes--is a very common phenomenon. While it is a big problem in India, doing it can ease certain problems and clear some hurdles. Baksheesh is also the term used by beggars if they want money from you and may refer to tips given those who provide you a service. Baksheesh is as ancient a part of Middle Eastern and Asian culture as anywhere else. It derives from the Arabic meaning a small gift. It refers as much to charity as to bribes.
Packaged goods show the Maximum Retail Price (MRP) right on the package. This includes taxes. Retailers are not supposed to charge more than this. Though this rule is adhered to at most places, at tourist destinations or remote places, you may be charged more. This is especially true for cold drinks like Coke or Pepsi, where a bottle (300 ml) is priced around ₹11-12 when the actual price is ₹10. Also, keep in mind that a surprising number of things do not come in packaged form. Do check for the authenticity of the MRP, as shopkeepers may put up a sticker of his own to charge more from you.

There are 22 official “scheduled” Indian languages, namely Assamese, Bengali, Bodo, Dogri, Gujarati, Hindi, Kannada, Kashmiri, Konkani, Maithili, Malayalam, Manipuri, Marathi, Nepali, Odia (also known as Oriya), Punjabi, Sanskrit, Santhali, Sindhi, Tamil, Telugu and Urdu. Among these languages, Hindi is the main Official Language of the Union Government with English acting as a subsidiary official language. Since it is a multi-lingual country, there is no National Language of India. Apart from these languages, there are hundreds of other less prominent languages like Tulu, Bhojpuri and Ladakhi that are the main spoken language of some places. Each Indian state has different Indian language. There are some places where speaking Hindi should be avoided such as Tamil Nadu and the Northeast, as Hindi is met with hostility from most of the locals there.
Hindi is also spoken as a second language. Dialects like Bhojpuri (Bihar) and the Pahadi dialects of Himachal Pradesh and Uttarakhand are similar to Hindi, however, may differ significantly from standard Hindi. Hindi, natively spoken by about 40% of the population, is the native tongue of the people from the "Hindi Belt"(including the capital, Delhi) in Northern India.
Fluency in English varies vastly based on education levels, occupation, age and region. In urban areas, getting by with English is generally not a problem. Code-switching between English and the native language (often in the same sentence) is very common among youngsters and is widely used in daily conversation, SMS (in Roman script), TV advertising, FM radio and Bollywood.
Most official signs are bilingual in the state language and English. Signs at railway stations are generally trilingual outside the Hindi-speaking belt.
Non-verbal communication also plays an important role. If they are nodding their head up and down, they mean yes or I agree. If they are shaking their head in a tilting motion from right to left and back (like a figure of eight), they mean I understand or I get what you said. If they shake their head sideways (left to right to left), they mean no. There are differences in the way these signs are used in northern and southern India. The back to forth mean yes and a vigorous left-right shift is no in northern India, though latter may be construed for yes in southern states like Tamil Nadu. Look for verbal cues that accompany these sounds (like 'aaan' for yes) in southern India to get the correct meaning.