The word kowtow comes from Mandarin Chinese, and literally means to "knock head." An alternative version of the word, ke tou, has the slightly less-painful translation "touch head." Both terms designate a style of prostration or worship, in which the user kneels down and touches his or her forehead to the ground or the floor.
Traditionally, people in imperial China kowtowed not only to the emperor, but also to lesser members of the court and bureaucracy. Interestingly, during the reigns of certain dog-loving emperors, the ordinary people and lesser court functionaries were forced to kowtow to the emperors' favorite Pekinese dogs, as well.
They would also kowtow to religious figures and objects, such as statues or images of the Buddha. Before the communist era, Han Chinese kowtowed to depictions of their ancestors or at the ancestral tombs during holidays; according to traditional beliefs, the ancestors became a family's heavenly intercessors and demi-gods after they passed away. This form of ancestor worship was one of the aspects of the "Four Olds" that the Red Guards sought to stamp out during the Cultural Revolution (1966-1976).
Although they received many more prostrations than they performed, even the Chinese emperors themselves would perform the kowtow before their ancestral shrines, and before important religious objects. The traditional full kowtow consisted of a pattern of kneeling, touching the forehead down three times, then standing up again; this pattern would be repeated in full three times, for a total of nine forehead touches. Commoners would then remain in a kneeling position until they were dismissed by the official to whom they had bowed. The emperor and court functionaries would stand after kowtowing, and take a seat.
When European diplomatic missions first approached the Qing Dynasty with requests for diplomatic and trade relations, the kowtow became a significant source of friction. A kowtow by the representative of a foreign state was required by court protocol, but it also signified that the foreign state was a tributary of China. Diplomats from European powers such as Great Britain adamantly refused to kowtow; as a result, some of them had to return home without ever having an audience with the emperor.