Introduction

Thailand's 76 provinces can be conveniently divided into five geographic and cultural regions.

North - Chiang Mai, hill tribes, and the Golden Traiangle
Isaan - the great undeveloped north-east - get off the beaten track and discover backcountry Thailand and some magnificent Khmer ruins
Central - Bangkok, lowlands and historic Thailand
East- beaches and islands within easy reach of Bangkok, and, oh yes,Pattaya
South- hundreds of kilometers of coastline and countless islands on both the Andaman Sea and the Gulf of Thailand, plus Phuket,Krabi,Ko Samui,Ko tao and many more of Thailand's famous beach spots

Cities

Bangkok - Thailand's bustling, frenetic capital
Ayutthaya - a historical city, world heritage site and the old capital city of Thailand
Chiang Mai - the capital of the North and the heart of Lanna culture
Chiang Rai - gateway to the Golden Triangle
Hat Yai - largest city in the Southern region
Kanchanaburi - home of the Bridge over the River Kwai
Nakhon Ratchasima (Khorat) - main city in the Isaan region
Pattaya - one of the main tourist destinations
Sukhothai - Thailand's first capital

Islands & beaches:
Ko Chang - once quiet island undergoing major tourism development
Ko Lanta - sleepy island near Krabi
Ko Pha Ngan - site of the famous Full Moon Party
Ko Phi Phi - backpacker favorite where The Beach was filmed
Ko Samet - the nearest island beach escape from Bangkok
Ko Samui - hippie mecca gone upmarket
Ko Tao - where the world learns to scuba dive
Phuket - the original Thai paradise island
Rai Leh - stunning beach by the limestone cliffs of Krabi
National Parks:
Ang Thong National Marine Park - in Surat Thani Province
Khao Yai National Park - in Isaan
Ko Chang National Park - in Trat Province
Similan Islands - in Phang Nga province
Tarutao National Park - in Satun Province

Understand

Thailand is the most popular tourist destination in South-East Asia, and for a reason. You can find almost anything here: thick jungle as green as can be, crystal blue beaches that feel more like a warm bath than a swim in the ocean and food that can curl your nose hairs while tap dancing across your taste buds. Exotic, yet safe and largely hassle-free; cheap, yet equipped with every modern amenity you need, there is something for every interest and every price bracket, from beach front backpacker bungalows to some of the best luxury hotels in the world. And despite the heavy flow of tourism, Thailand retains its quintessential Thainess, with a culture and history all its own and a carefree people famed for their smiles and their fun-seeking sanuk lifestyle. Many travelers come to Thailand and extend their stay well beyond their original plans and others never find a reason to leave. Whatever your cup of tea is, they know how to make it Thailand.
This is not to say that Thailand doesn't have its downsides, including the considerable growing pains of an economy where an agricultural laborer is lucky to earn 40 baht per day while the nouveau riche cruise past in their BMWs, and a highly visible sex tourism industry. Bangkok, the capital, is notorious for its traffic jams and rampant development has wrecked much of once-beautiful Pattaya and Phuket. In heavily touristed areas, some lowlifes have made scamming tourists into an art form.

History
A unified Thai kingdom was established in the mid-14th century. Known as Siam until 1939, Thailand is the only South-East Asian country never to have been taken over by a European power, and fiercely proud of the fact. A bloodless revolution in 1932 led to a constitutional monarchy. In alliance with Japan during World War II, Thailand became a US ally following the conflict. After a string of military dictatorships and quickly toppled civilian presidents, Thailand finally stabilized into a fair approximation of a democracy and the economy, hobbled by the 1997 Asian economic crisis, is booming once again. Above it all presides the King Bhumibol Adulyadej (Rama IX), the world's longest-reigning monarch and a deeply loved and respected figure of near-mythic proportions.
In September 2006, a swift and bloodless military coup endorsed by the King overthrew the previous democratically elected but widely criticized government, promising elections in late 2007. Although martial law still applies and political gatherings are restricted, there has been no violence, no curfews are in effect, there is no longer any significant military presence in public places, and all services are functioning normally.

Climate
Thailand is largely tropical, so it's hot and humid all year around with temperatures in the 28-35°C range (82-95°F), a degree of relief provided only in the mountains in the far north of Thailand. The careful observer will, however, note three seasons:
Cool: From November to the end of February, it doesn't rain much and temperatures are at their lowest, although you will barely notice the difference in the south and will only need to pack a sweater if hiking in the northern mountains, where temperatures can fall as low as 5°C. This is the most popular time to visit and, especially around Christmas and New Year's, finding flights and accommodation can be expensive and difficult.
Hot: From March to June, Thailand swelters in temperatures as high as 40°C (104°F). Pleasant enough when sitting on the beach with a drink in hand, but not the best time of year to go temple-tramping in Bangkok.
Rainy: From July to October, although it only really gets underway in September, tropical monsoons hit most of the country. This doesn't mean it rains non-stop, but when it does it pours and flooding is not uncommon.
There are local deviations to these general patterns. In particular, the south-east coast of Thailand (including Ko Samui) has the rains reversed, with the peak season being May-October and the rainy off season in November-February

People
Thailand's people are largely Thais, although there are significant minorities of Chinese and assimilated Thai-Chinese throughout the country, Muslims in the south near the Malaysian border and hill tribes such as the Karen and the Hmong in the north of the country. The overwhelmingly dominant religion (95%) is Theraveda Buddhism, although Confucianism, Islam, Christianity and animist faiths also jostle for position.

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.

Calendar
In addition to the Gregorian calendar, Thailand also uses the Thai solar calendar, which is 543 years ahead. Thus, Thai year 2550 corresponds to the Western year 2007. Thai dates in English are often written as B.E., short for "Buddhist Era".
Some Thai holidays are still calculated with the older Thai lunar calendar, so their dates change every year.

Holidays
Thailand has a lot of holidays, mostly related to Buddhism and the monarchy. Nobody celebrates all of them, except for banks, which seem to be closed a lot.
Makha Bucha falls on the full moon in of the fourth Lunar month, which usually falls in February or March, and commemorates the spontaneous gathering of 1,250 people before the Buddha, which led to their ordination and subsequent enlightenment. At temples in Bangkok and throughout Thailand, Buddhists carry candles and walk around the main shrine three times in a clockwise direction.
During Chinese New Year, Chinese Thais, who are numerous in Bangkok, celebrate by cleaning their houses and offering food to their ancestors. This is, mainly, a time where feasts are abound. Visit Bangkok's Chinatown or Yaowarat to fully embrace the festivity.
Songkran (สงกรานต์) - undoubtedly the most fun holiday - is the celebration of the Thai New Year, sometime in April (officially April 13th to 15th, but the date varies in some locations). What started off as polite ritual to wash away the sins of the prior year has evolved into the world's largest water fight, which lasts for three full days. Water pistols and Super Soakers are advised and are on sale everywhere. The best places to participate are Chiang Mai, the Khao San Road area in Bangkok and holiday resorts like Pattaya, Ko Samui and Phuket. Be advised that you will get very wet, this is not a spectator sport. In recent years, the water-throwing has been getting more and more unpleasant as people have started splashing iced water onto each other. It is advisable to wear dark clothing, as light colors may become transparent when wet.
Loy Krathong (ลอยกระทง) falls on the first full moon day in November, when people head to rivers, lakes and even hotel swimming pools to float flower and candle-laden banana-leaf (or, these days, styrofoam) floats called krathong. The krathong is meant as a thank you offering to the river goddess who gives life to the people. Thais also believe that this is a good time to float away your bad luck and many will place a few strand of hair or finger nail clippings in the kratong. According to tradition, if you make a wish when you set down your krathong and it floats out of sight before the candle burns out, your wish will come true. Some provinces have their own version of Loy Krathong, such as Sukhothai where a spectacular show takes place. To the North, Chiang Mai and Chiang Rai, have their own unique tradition of floating Kom or lit laterns. This sight can be breath-taking as the sky is suddenly filled with lights, rivalling the full moon.
Coronation Day (May 5) commemorates the crowning of the current King in 1950 (although his reign actually began on June 9 1946 - making him not only the longest-serving monarch in Thai history, but also the world's longest-serving current Head of State).
The King's Birthday (December 5) is the country's National Day and also celebrated as Father's Day, when Thais pay respect to and show their love for His Majesty the King. Buildings and homes are decorated with the King's flag (yellow with his insignia in the middle) and his portrait. Government buildings, as well as commercial buildings, are decorated with lights. In Old Bangkok (Rattanakosin) in particular, around the Royal Palace, you will see lavish light displays on trees, buildings, and the roads. The Queen's Birthday (August 12) is Mother's Day, and is celebrated similarly if with a little less pomp.