The line between soups (ต้ม tom, literally just “boiled”) and curries (เเกง kaeng) is a little fuzzy, and many dishes the Thais call curries would be soups to an Indian. A plate of rice with a ladleful of a curry or two on top, known as khao kaeng (ข้าวเเกง), is a very popular quick meal if eating alone.
Tom yam kung (ต้มยำกุ้ง) is the quintessential Thai dish, a sour soup with prawns, lemongrass and galangal. The real thing is quite spicy, but toned-down versions are often available on request.
Tom kha kai (ต้มข่าไก่) is the Thai version of chicken soup in a rich galangal-flavored coconut stock, with mushrooms and not a few chillies.
Kaeng daeng (เเกงเเดง, “red curry”) and kaeng phet (เเกงเผ็ด, “hot curry”) are the same dish and, as you might guess, this coconut-based dish can be spicy. Red curry with roast duck (kaeng pet yaang เเกงเป็ดย่าง) is particularly popular.
Kaeng khio-waan (เเกงเขียวหวาน), sweet green curry, is a coconut-based curry with strong accents of lemongrass and kaffir lime. Usually milder than the red variety.
Kaeng som (เเกงส้ม), orange curry, is more like tamarind soup than curry, usually served with pieces of herb omelette in the soup.