How to Determine Orientation in 3-Dimensional Space?

[Amer]

In 2 dimensions we have clockwise and counter clockwise orientation, in 3 dimensions how to determine orientation in the space.
for example: how to name the vertices of a solid like a cube or a tetrahedron.

 

[Almsco]

The orientation of a 3-dimensional object can be determined by looking at the orientation of its vertices. For example, the vertices of a cube can be labeled A, B, C, D, E, F, G and H, with ABCD being on the top plane and EFGH being the bottom plane. The orientation of each vertex can then be determined by its position relative to the other vertices. For example, vertex A would be oriented in a counter-clockwise direction if viewed from above, while vertex B would be oriented in a clockwise direction if viewed from the same angle. Similarly, the vertices of a tetrahedron can be labeled A, B, C and D, with the orientation of each vertex determined by its position relative to the other vertices.