Stress at a point is a vector

In three dimensions stress has nine components.

In three dimensions stress has six independent components.

At a point in plane stress there are three independent stress components.

At a point in plane stress there are always four zero stress components.

If the shear stress on the left surface of an imaginary cut is upward and defined as positive, then on the right surface of the imaginary cut it is downward and negative.

A stress element can be drawn to any scale.

A stress element can be drawn at any orientation.

Stress components are opposite in direction on the two surfaces of an imaginary cut.

Stress components have opposite signs on the two surfaces of an imaginary cut.