Culture
Mainland Thai culture is heavily influenced by Buddhism. However, unlike the Buddhist countries of East Asia, Thailand's Buddhists follow the Therevada school, which is arguably closer to its Indian roots and places a heavier emphasis on monasticism. Thai temples known as wats, resplendent with gold and easily identifiable thanks to their ornate, multicolored, pointy roofs are ubiquitous and becoming an orange-robed monk for a short period, typically the three-month rainy season, is a common rite of passage for young Thai boys and men.
One pre-Buddhist tradition that still survives is the spirit house (ศาลพระภูมิ saan phraphuum), usually found at the corner of any house or business, which houses spirits so they don't enter the house and cause trouble. The grander the building, the larger the spirit house, and buildings placed in particularly unlucky spots may have very large ones. Perhaps the most famous spirit house in Thailand is the Erawan Shrine in central Bangkok, which protects the Erawan Hotel (now the Grand Hyatt Erawan) - built in 1956 on a former execution ground - and is now one of the busiest and most popular shrines in the city.
Some traditional arts popular in Thailand include traditional Thai dancing and music, based on religious rituals and court entertainment. Famously brutal Thai boxing (muay Thai), derived from the military training of Thai warriors, is undoubtedly the country's best known indigenous sport.
In addition to the mainland Thai culture, there are many other cultures in Thailand including those of the "hill tribes" in the northern mountainous regions of Thailand (e.g., Hmong, Karen, Lisu, Lahu, Akha), the southern Muslims, and indigenous island peoples of the Andaman Sea.
Respect
Thais are a polite people and, while remarkably tolerant of foreigners gallivanting on their beaches and with their women, you'll find that you will get more respect if you in turn treat them and their customs with respect.
The Wai
The traditional greeting known as the wai, where you press your hands together as is in prayer and bow slightly, is derived from the Hindu cultural influence from India, and still widely practised. Among Thais, there are strict rules of hierarchy that dictate how and when the wai should be given. In brief, inferiors salute superiors first. You should not wai service people or street vendors. The higher your hands go, the more respectful you are. You will also often see Thais doing a wai as they walk past temples and spirit houses. As a foreign visitor, you are not expected to know how to wai, nor to reciprocate when wai'd to; while you're unlikely to cause offense if you do, you may well look slightly ridiculous. If somebody makes a wai to you, a slight bow alone is more than sufficient for ordinary occasions, and for business most Thais will shake hands with foreigners instead of waiing anyway.
Dress
Personal appearance is very important in Thailand as a measure of respect to other people, so clothes should be neat, clean, and free from holes or tears. Traditionally, Thais are modest and conservative dressers, and thus clothing should avoid showing a lot of skin. Pants are preferable to shorts, blouses should have capped sleeves, and if tank tops are worn, the straps should be thick (i.e., not spaghetti straps). Thai men generally wear pants, and most Thais view an adult man wearing shorts as fairly ridiculous; shorts are primarily worn by laborers and schoolchildren. Shorts should be knee length or more, if worn at all. Swimsuits should not be revealing -- many Thais swim in full clothing. You will find that dressing appropriately means that you are shown more respect in return. This translates in many ways, even sometimes lowering initial offering prices at markets. While some allowance is made for the differing customs of foreigners, Thais respond more positively to well-dressed Westerners.
Remember that you will frequently need to remove your shoes when entering temples or homes, so wear shoes that slip on and off easily. Flip-flops, hiking sandals, and clog-type shoes are usually a good pragmatic choice for traveling in Thailand; only in the most top-end establishments are shoes required. Taking off one's shoes at temples and private homes is expected and mandatory, and this may even be requested at some shops.
It is best to play it safe with wats and other sacred sites in Thailand; your dress should be unambiguously modest. For men, ankle-length pants are mandatory; on top, t-shirts are acceptable, though a button-front or polo shirt would be best. Many recommend that women wear only full length dresses and skirts; you should make sure that your clothing covers at least your shoulders and your knees and some places may require that you wear ankle-length pants or skirts and long sleeved tops. Shorts and sleeveless shirts are highly inappropriate, as are short skirts. The rules are even more strict for foreign visitors, so even if you see a local in shorts it's not OK for everyone.
It's hard to find agreement on what dress is conservative enough for women. Women should never go topless on the beach, especially beaches in national parks, as this is illegal and most Thais consider it offensive in the extreme. Women are sometimes advised to wear a T-shirt over their swimming gear; this is more important at primarily-Thai beach resorts, and will be almost entirely ignored at the most heavily westernized areas. Outside of sacred sites or the beach normal western dress is generally acceptable.
Medical Services
All tourism destinations and provincial capitals have hospitals and clinics staffed by well-trained doctors and nurse. In the case of an emergency, an ambulance can be summoned from any private hospital.
Vaccinations : As in most other countries, visitors do not require vaccinations unless coming from or passing through a designated contaminated area
