Here are some informations about VietNam
Country name:  The Socialist Republic of Vietnam
Population: 90.5 million
Capital City: Hanoi city, second big city
People: 54 Ethnic minorities are living together
Language: Vietnamese
Currency: Vietnam Dong (VND)
Time Zone: GMT +7 Hours
International Dialing Code: +84
Vietnam is a small but majestic and beautifull country, Will bring for travellers an exciting mix of adventure and culture. The country’s captivating natural wonders span from the mountainous north and the fertile plains of the Mekong Delta, to the spectacular coastline of central Vietnam and the magnificent Halong Bay. With an intriguing history spanning back over 4,000 years, including occupations from both the Chinese and French, the country’s architecture and cuisine is a fascinating testament to cultural diversity.
Passport and visa
Passports should be valid for six months from the date of entry into Vietnam. We recommend you make a photocopy of your passport and keep it somewhere separate, or scan it and keep it in an accessible email account.
Some nationalities may be able to enter Vietnam without a prearranged visa for a certain amount of time. Below is a list of visa exemptions and duration of stay.
30-day duration: Singapore, Thailand, Malaysia, Philippines, Laos and Indonesia and Cambodia.
15-day duration: Japan, South Korea, Sweden, Finland, Denmark, Norway, Germany, France, Spain, Italy and the United Kingdom. 
As of February 1st, 2017, Vietnam has introduced an e-visa pilot scheme which is scheduled to last 2 years. Visitors are currently able to apply online for 30-day, single entry visa for Vietnam.
The following countries are allowed to apply for the e-visa:
Armenia, Argentina, Azerbaijan, Belarus, Brunei, Bulgaria, Chile, China, Columbia, Czech Republic, Cuba, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, Kazakhstan, Luxembourg, Mongolia, Myanmar, Norway, Panama, Peru, Philippines, Poland, Romania, Russia, Slovakia, South Korea, Spain, Sweden, Timor-Leste, United Kingdom, United States, Uruguay and Venezuela.
If you are not from one of these countries or you wish to apply for a longer visa or a multiple entry visa, you will have to apply through the traditional method of contacting the embassy or through a third party. 
Goodmorningvietnam can help you to arrange visas at reduced cost for visitors who book one of our tours. Applications must be made to us no later than 14 days before travel. Please contact us for the most recent information.
There is also a stamp fee which is payable on arrival at the airport. The price depends on the type and duration of your visa.
Currency
The official currency in Vietnam is the Dong (VND) which is a non-convertible currency. American dollars are widely accepted in larger stores and supermarkets. Visa and MasterCard are accepted in many hotels, restaurants and large stores, especially in the bigger cities. ATM are widely available throughout the country, and there are a number of international banks in Hanoi and Ho Chi Minh City.
Phones & Internet service
The Vietnamese postal service is reliable and there are also courier services widely available. Do not put postcards into letter boxes, give them to your hotel to post or go to a post office.
Telephone connections to the rest of the world are widely available, however they aren’t cheap. A Vietnamese SIM card is a less expensive way of calling other countries, however your phone will need to be unlocked in order for it to work.
Internet access is available in all major hotels and you will find WiFi in most cafes in developed areas.
Traffic & Transportation
The traffic in Vietnam is busy, but slow. It may look like chaos but don’t be frightened to cross the road. Simply make your way shaking your whole hand at waist height. You’ll soon see other people doing the same.
Taxis are a popular way of getting around Hanoi but make sure you use a reputable company such as Mai Linh, VinaSun, Taxi Group or Thanh Cong taxis. A typical  journey should cost around 50,000 VND for 4km  but should remmenber prices tend to increase at night.
If you are in a developed area, a cyclo is a fun form of transport and should cost no more than 100,000 VND per journey.
Motorbike taxis: Travel by unlicensed motorbike is not safe and under no circumstances is this sanctioned or recommended by Goodmorningvietnam.  Please note that this form of transport is not usually covered by insurance. Please check the fine print of your travel insurance policy to be sure of your cover.
Weather
Vietnam has a diverse climate that varies significantly from region to region:
The North (HaNoi, Halong, Sapa, Ninh Binh, Hagiang…)

The Centre (Hue, Danang, Hoian, Nhatrang..)

Please note: The weather can be very unpredictable so it may be a good idea to carry an umbrella or raincoat with you. You can purchase these from supermarkets and general stores. 
Health and Safety
Health and well-being
Please be aware that your health can be at risk in Vietnam due to poor sanitation and lack of effective medical facilities. Rural areas may not have pharmacies and hospitals so make sure you travel with a full supply of any prescribed medicine you take. If you need medical assistance, we suggest The Family Medical Practice in both Hanoi and Ho Chi Minh City. Every traveller is responsible for his or her own health.
First and foremost, make sure that you have travel insurance for your trip. You should also consult your doctor or local travel clinic for the latest information and advice on travelling to Vietnam before departure.
If you have a medical condition or allergy of which requires particular attention, carry a doctor’s letter with you that describes the nature of the condition and treatment needed. We also recommend you pack a medical kit, including Paracetamol and a diarrhea remedy.
Vaccinations
Before travelling, please ensure you have adequate protection against disease.  Contact your doctor for the latest medical advice on the vaccinations you need, no less than two months before your departure.  Be aware that there is a malaria risk in rural parts of Vietnam.
Travel insurance (recommended) 
Goodmorningvietnam does everything possible to ensure a safe and enjoyable trip. However, travel inevitably involves some unavoidable risk. Travel insurance is a cost effective way of protecting yourself and your equipment should any problems occur such as cancelled trips, delays, medical emergencies, baggage loss or damage. Please also make sure your travel insurance covers all activities planned on your trip so you can enjoy peace of mind during your journey.
Culture & Customs
Etiquette and cultural differences
Experiencing different cultures is one of the joys of travelling, and it is important that these differences are respected. Knowing a few important customs of the Vietnamese people will help make your visit more enjoyable:

When passing something to another person, use both your hands together or just your right hand. Never use just your left hand.
Food and drink
Vietnamese food is fragrant, exciting and healthy.  Around the country, you will find a delicious variety on offer, influenced from France, Thailand and even India.
The most popular dish is called “pho” and is often referred to as the "soul of the nation". Simpy put, it’s a noodle soup dish eaten every day, predominantly for breakfast. It is served in most Vietnamese restaurants and street food vendors. Don’t be afraid to try the street food, which is often the best food in the country. There are plenty of options, including:

It is not advisable to drink tap water in Vietnam. Bottled water is cheap and widely available.
Public holidays

Helpful tips
Donations and gift giving
Although there is poverty in certain areas of Vietnam, please read the following points about donations and gift giving.
Do not give money to people begging, especially children. This reinforces the belief that begging is an acceptable way to make a living. If children make money from begging, their parents are less likely to send them to school. Children working on the streets are also vulnerable to abuse.
However in many places, it is considered acceptable to give to money to disabled people or the elderly.
Giving money and goods to beggars can accentuate an unequal relationship between locals and visitors, with tourists being seen as purely money givers.
Do not give sweets to children in villages that we visit.
Do not feel that you necessarily have to give material things. Sometimes, giving your friendship, time and interest to locals can be the best gift of all.
Tipping
Tipping is a personal matter and travellers are encouraged to tip any amount they feel is appropriate. For your convenience, we have included a suggested tipping guide below:

Pre-departure checklist

Please note: Domestic airlines do impose restrictions on baggage at approx 20kg maximum, so travel lightly where possible. Train cabins around the country, and boat cabins in Halong Bay have limited space so consider this when packing
According to the hotel policy in VietNam , Check in time after 02PM, Checck out time before 12AM