Four regional cuisines
Thai food is not one cuisine but four, each shaped by its geography. Central Thai cuisine — what most foreigners think of as Thai food — comes from Bangkok and the rice plains around it. It balances sweet, sour, salty, and spicy with coconut milk, fish sauce, palm sugar, and lime. Dishes like green curry, tom yum, and pad thai belong to this region.
Northern (Lanna) cuisine from Chiang Mai is milder, herbier, and uses sticky rice as the staple. Khao soi (curry noodle soup), sai oua (herb sausage), and nam prik dips define the north. Northeastern (Isaan) cuisine from the Lao border is bold, salty, fermented, and grilled — som tam (papaya salad), gai yang (grilled chicken), laab (minced meat salad), and sticky rice. Southern Thai food, influenced by Malay-Muslim and Indian traditions, is the spiciest of all: massaman curry, khua kling (dry curry), and gaeng som (sour curry).
Iconic dishes
A short list of dishes worth seeking out: Pad Thai (stir-fried noodles, tamarind-sweet, peanut topping), Tom Yum Goong (sour-spicy shrimp soup with lemongrass and galangal), Massaman Curry (mild, peanutty, often beef or chicken), Som Tam (green papaya salad pounded with chilies and lime), Khao Soi (Northern crispy-and-soft curry noodle soup), Larb (minced meat salad with toasted rice and herbs), Mango Sticky Rice (the dessert benchmark, March-June peak season), and Khao Pad (Thai fried rice — best as a quick lunch).
Spice levels and ordering
Thai spice operates on a different scale than most cuisines. A "medium" som tam in a Bangkok food court can outburn a habanero hot sauce. Useful phrases: phet noi (a little spicy, the tourist starting point), phet (medium, hot for most foreigners), phet phet or phet mak (very spicy, take care), and mai phet (not spicy, sometimes still has heat). At tourist-area restaurants, dishes are toned down by default; in local spots, ask explicitly.
Vegetarian (jay) food
Thai vegetarian options have improved dramatically in the last decade. Jay is the strict vegan version — no animal products, no garlic, no onion — marked by yellow flags with red Thai writing, especially during the Vegetarian Festival in October. Mangsawirat is regular vegetarian, allowing dairy and eggs. Both labels make ordering easy. Even non-vegetarian restaurants will usually adapt stir-fries with tofu (gin jay or tao hu) on request.
Eating customs
Thai meals are shared. Order multiple dishes, place them in the center of the table, and serve yourself onto a plate of rice. The fork pushes food onto the spoon, which is what goes in your mouth — using a fork directly is informal at best. Chopsticks appear only with noodle soups (chopsticks for the noodles, spoon for broth). Tipping is not traditional but 20-50 baht is appreciated at sit-down restaurants. Slurping noodles is fine; finishing every grain of rice is a polite norm — leaving rice suggests you did not enjoy it.
How to order like a local
At a casual lunch place, order one rice or noodle dish per person plus 1-2 shared dishes for the table. Ask the staff what is good today — they will steer you correctly. At Isaan restaurants, the holy trinity is som tam, gai yang, and sticky rice. At a noodle stall, point at what others are eating and say "ao baeb nan" (I will have that one). Nearly every restaurant has English menus or photos in tourist Bangkok — language is rarely a barrier.