Translations:Assembly Basic Tutorial/5/en

In FreeCAD every object in 3D space has its own coordinate system. This local system is set in relation to its parent system by a transformation, its placement. The object's placement defines how the local geometry needs to be translated and rotated to be expressed in the parents system. Hence if you move a part by editing its placement property, you don't change the part, only the transformation of its coordinate system into the parent system. Imagine a simple box created in the Part workbench. Once created, the length parameter changes the box's dimension in the local x direction. As the placement is empty, it's also the global x direction. If you rotate the part by setting a rotation axis and an angle, the length will still be in local x direction, however, visually it will not change on x anymore as the visuals are presented in the global coordinate system. The box geometry has not changed, just the visualization is transformed.