Tribhuvan International Airport (TIA) in Kathmandu is the only international airport in Nepal. The national flag carrier, Nepal Airlines, and other international airlines directly connect Kathmandu with major cities around the world. Alternatively, you can travel to Nepal via India.

All visitors coming to Nepal by land can enter through any of these entry points on the India- Nepal Border: 
       Pani Tanki/ Kakarbhitta 
       Raxual/ Birgunj 
       Sunauli/ Belahiya 
       Rupaidiya/ Nepalgunj
       Mohana/ Dhangadi 
       Banbasa/ Mahendranagar, Gaddachauki 
       Khasa, Liping/ Tatopani on the Tibet,China-Nepal border respectively
Overland tourists entering the country with their vehicles must possess an international carnet or complete customs formalities.

Nepal Airlines is the national flag carrier of Nepal with flights to/from Delhi, Kuala Lumpur, Dubai, Bangkok, Doha and Hong Kong.
Other international airlines operating from/ to Kathmandu are:

There are taxi-drivers, travel agents and hoteliers waiting outside the airport terminal to offer their services to you. Pre-paid taxi service is also available at the airport.
Is there an airport tax in Nepal? 
Yes. It is already included in your ticket. But on domestic routes, a separate airport tax of Rs.200 is charged before boarding.

All foreign nationals, except Indians, need visas to enter Nepal. Multiple entry visas for 15 days (US$ 25 or equivalent convertible currency), 30 days (US$ 40) or 90 days (US$ 100) can be obtained from any Nepalese embassy or consulate. You can also get a visa on arrival at the Tribhuvan International Airport , Kathmandu or at the Immigration Office at the entry points of Nepal. 

Tourist visas can be extended for a period of 120 days at the Immigration Department in Kathmandu or Pokhara. However, nationals of the following countries will not get visa on arrival at the immigration entry points of Nepal: Afghanistan, Cameroon, Ethiopia, Ghana, Iraq, Liberia, Nigeria, Palestine, Somalia, Swaziland and Zimbabwe. They need to obtain visas from Nepalese embassies or diplomatic missions in their respective countries prior to their arrival in Nepal. 

Gratis (Free) Visa for 30 days is available only for nationals of South Asian countries like Bangladesh, Bhutan, Maldives, Pakistan and Sri Lanka for the first visit in one visa year (January to December). However, a visa fee is required for its extension beyond the 30 days. 

Indian nationals do not require a visa to enter Nepal.

For more information, please, contact Department of Immigration, Kalikasthan, Kathmandu
Tel :    00977-1-4433934 / 4429660 / 4438862 / 4438868
Email :   mail@immi.gov.np 
Web : www.immi.gov.np

As per the Nepalese Immigration, Indian Nationals Traveling to Nepal must posses any One of the following documents :- 

A valid passport and one passport size photo with a light background . Immigration Department has not specified the size of the passport-size photo. Visa can be obtained only through payment of cash in the following currency : Euro, Swiss Franc, Pound Sterling, US dollar, Australian dollar, Canadian dollar, Hong-kong dollar, Singapore dollar and Japanese Yen.
Credit Card, Indian currency or Nepalese currency are not accepted for payment of Visa fee.

Light, loose garments are recommended in spring (March, April and May) and summer (June, July and August), while woolens and jackets or similar warm clothings are needed from November to February.

The Nepalese currency is the rupee and is divided into 100 paisa. Bank notes come in denominations of Rs. 1, 2, 5, 10, 20, 50, 100, 500 and 1,000. Coins are of 1, 2 and 5 rupee denomination.

It is illegal to exchange foreign currency with persons and organizations other than those authorized such as banks, hotels and licensed money changers. Nepalese banks do not accept Indian currency of denomination of Rs. 500 and 1000. You will find the exchange rates for different currencies in the Nepalese papers. In order to exchange surplus rupees at the time of your departure, please retain your encashment receipts.

There are ATMS in Kathmandu, Pokhara and other big cities in Nepal that accept AMERICAN EXPRESS, VISA and MASTERCARD.

Major hotels, restaurants and curio shops accept AMERICAN EXPRESS, VISA and MASTERCARD. You can contact the banks for credit card services.

You can draw funds against your AMERICAN EXPRESS, VISA and MASTERCARD cards in Kathmandu. The service premiums for doing this, however, could be high. You can also have money wired directly to Kathmandu through any major bank within two to three working days.

Yes.

Although specific immunization is not required to enter Nepal, it is, however, best to protect yourself against diseases such hepatitis, meningitis and Japanese encephalitis. Malaria has been reported in the Terai plains of Nepal, so take precautions against being bitten by mosquitoes. Please notify the authorities or the hotel of any symptoms of bird or swine flu or any endemic.

Use only bottled mineral water or boiled and filtered water only. Always wash your hands before eating. Do not eat unpeeled fruits or vegetables unless they have been thoroughly washed.

Because of its elevation, Nepal can be divided into three zones – the high mountains, the mid-hills and the flat plains called the Terai. The Everest, Langtang and Annpurna trekking destinations in the mountains are cool throughout the year. The mid-hills, including Kathmandu and Pokhara, are cool except in the summer months from May to July. Temperatures in these cities during the summer remain much cooler than in many cities of the region. Lumbini, Chitwan and Janakpur in the Terai plains are hot in summer (March –July) but cold in winter (December-February). So if you are going trekking, the best months for walking are between September and November and between February and May when the weather is fair during the day and the temperatures do not drop rapidly during the night.

There are well-equipped general and specialized hospitals, nursing homes and private clinics manned by very competitive doctors in Kathmandu, Pokhara and other cities if you fall sick. Your hotel will provide good advice on the matter.

Helicopter services are available should you fall sick or meet with an accident while trekking. However, such rescue services are expensive. So comprehensive travel insurance is advised to cover emergencies like helicopter rescue and medical treatment.

Public toilets can be used for a small fee. But visitors are advised to use the toilets at the shopping malls, stores and restaurants which are cleaner.

The country code for Nepal is 977 and the area code for Kathmandu is 01, for Pokhara 061, Chitwan 056 and Lumbini 071.

Nepali time is GMT plus 5 hours 45 minutes.

Tourists of all nationalities including Indians, who are interested to visit general trekking areas of Nepal, are required to receive TIMS Card through one of the following offices: 
                           Kathmandu (NTB office, TAAN office and Government registered trekking companies) 
                           Pokhara (NTB office, TAAN office and Government registered trekking companies) 

To obtain a TIMS Card you need a photo copy of your passport details and two passport-size photographs. 20 US $ equivalent Nepalese Rupees must be paid to obtain TIMS Card from NTB offices or TAAN offices which issue TIMS card only for Free Individual Trekkers (FIT) who do not take the services of both Guide and Porter. However, 10 US $ equivalent Nepalese Rupees must be paid for obtaining TIMS card for Group Trekkers (GT- who take the services of both Guide and Porter) only from registered trekking agencies in Nepal. The TIMS card is non-transferable, non-endorsable and valid only for one entry for prescribed area and duration.

 Opening hours :

Electricity in Nepal is 230 volts, alternating at 50 cycles per second. A voltage converter is needed for a device that does not accept 230 volts at 50 MHz. Sockets in Nepal accept only round three or two pins. So if your electrical device uses flat pins, please bring a universal electric plug adaptor.