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 Theravada Buddhism, although Confucianism, Islam, Christianity and animist faiths also jostle for position.
The people respects the royalty, the King and the Queen, very much. Even pointing fingers to the picture of them is considered bad.
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.
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.
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 (มาฆบูชา) - 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 (ตรุษจีน), Chinese Thais, who are numerous in Bangkok, celebrate by cleaning their houses and offering food to their ancestors. This is mainly a time of abundant feasting. 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 the twelveth month in Luna calendar, usually on 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 (กระทง). 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 krathong. 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 lanterns balloon. This sight can be breath-taking as the sky is suddenly filled with lights, rivaling 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. 
