Le Chatelier's Principle: A principle that states when a system at equilibrium is disturbed by a change in temperature, pressure, or concentration of components, the system will shift its equilibrium position so as to counteract the effect of the disturbance.
Equilibrium:The state where both reactants and products are present in concentrations which have no further tendency to change with time.
Concentration:The amount of a substance per defined space. It's usually measured in moles per liter (mol/L).