As we know, the equilibrium may be moved by any "outside disturbance". In the case of demand and supply, this would be a change in one of the determinants of demand or supply, other than the price of the product, which would lead to a shift of either one of the curves.
Supply Curve (R) + Demand Curve (R) = Equilibrium Price (Uncertain), Equilibrium Quantity (+)
SC (R) + DC (L) = EP (-), EQ (U)
SC (L) + DC (R) = EP (+), EQ (U)
SC (L) + DC (L) = EP (U), EQ (-)