Thai massage is a type of massage that involves stretching and deep massage. It is known in Thailand as "nuat phaen boran" - literally, the ancient-manner massage (nuat = massage, phaen = manner, boran = ancient), or just "nuat phaen thai". Other names for this style of massage are: northern-style Thai massage, Buntautuk style, Old Medicine Hospital Style, traditional Thai massage, Traditional Thai Medical Massage, Thai Yoga, Thai Yoga Massage, yoga massage, Thai classical massage, Thai bodywork, passive yoga or assisted yoga.
During the massage, the receiver is put into yoga-like positions. With the Northern style, there are a lot of stretching movements, whereas with the Southern style, emphasis is given to acupressure. The massage recipient wears loose fitting closes such as pyjamas and lies on a mat or firm mattress on the floor (it can be done solo or in a group of a dozen or so clients in the same large room). The massage giver leans on the recipient's body using hands and forearms to apply firm rhythmic pressure to almost every part of the receiver's body. The massage generally follows the Sen Energy lines on the body (the Sen are comparable to Chinese meridians). In some gestures, the legs and feet of the giver are used to fixate the body or limbs of the recipient. In other gestures, hands fixate the body, while the feet do the massaging action. Usually no oil is applied, but sometimes a hot herbal compress is used to warm and soothe the receiver's body. A full course of Thai massage typically lasts two hours or more and includes pulling fingers, toes, ears etc, cracking the knuckles, walking on the recipient's back, arching the recipient's back in a rolling action etc. There is a standard procedure and rhythm to the massage.
More information about Thai massage can be found on Wikipedia.