Parallel structures are characterized by closed kinematics chains. Compared with conventional structures, which have serially arranged axes and are thus characterized by open kinematics chains, parallel structures have a variety of advantages. These primarily include lower moved mass, high dynamics, the high number of possible repeating parts, and the advantageous integration of measures in the control system that are relevant to accuracy. The following presentation classifies parallel structures with six degrees of freedom according to the type of drive used. Based on free-form surface machining in die and mold making, kinematics requirements will be explained and various concepts regarding kinematics, structure.loading, and stiffness will also be discussed. Finally, a preferable solution will be provided in the summary.