The right hand rule for a positive axis

If you're new to modeling in 3D, it may be confusing trying to always remember which direction of an axis is its positive direction. Follow this simple rule and you'll always get it right!

The direction of any positive axis in a Cartesian coordinate system can be determined by placing your right hand palm up facing you and your thumb pointing to the right. Your thumb will point along the positive X axis and your index finger will point along the positive Y axis. Now close the rest of your fingers but leave your middle finger pointing towards you. It indicates the direction of the positive Z axis.