The problem of postural stability is the unifying element of contemporary kinesiology. In investigations of its basic principles it is important to use unequivocally characterized and clearly differentiated terms which will assist better understanding and restrict the spread of generally popular errors. The most frequent ones include mistakingCOPfor the centre of gravity (COM) and the idea that by means of a record of the examination on tensimetric planes it is possible to follow the movement of the centre of gravity. Also descriptions of „balanced reactions“ are often very confusing.

        Key words: postural stability, posture, COP