Grassman Numbers

They are values generated by Grassman function.
Their property is that they are anticommutative. That is:

If \(\theta_a\) and \(\theta_b\) are two Grassman numbers,
then \(\theta_A\) \(\theta_B\) = -\(\theta_B\) \(\theta_A\)

Also, \(\theta^2=0\)

This property is used to describe the field values of Fermions and that can be used to explain the Pauli Exclusion Principle.
They are used to complete the missing elementary particles of the standard model in the theory of Supersymmetry