Permeability:A measure of how easily a material can support an external magnetic field. In vacuum or air, this constant is denoted as $\mu_0$.
Ampere's Law:$\oint B \cdot dl = \mu_0 I_{enc}$; This law relates integrated magnetic fields around closed loops to electric currents passing through those loops.
Right-Hand Rule:A mnemonic for understanding orientation conventions for vectors in three dimensions related to electromagnetic phenomena. Used to find directions of fields and forces.