The position of the supply curve moves due to a change in one of the determinants of supply. Shifts can be positive (to the right) or negative (to the left). If supply shifts there is an equal change in supply at every price level.
Below is a diagram to show the two types of shift that can occur - an inwards and outwards shift. These shifts can be caused because of a variety of reasons. For instance if the cost of a raw material changes then this is likely to change a firm's supply decision as the more expensive a good is to produce, the fewer they will supply (inward shift). On the other hand, if a good is less expensive to produce, the more of the product they will supply (outward shift).
However, when evaluating a supply curve shift it is important to take into account the significance of the shift. This is because large supply curve shifts will have a larger impact on the market equilibrium compared to smaller supply curve shifts. The significance of the supply curve shift will also depend on the elasticity of the curves. As inelastic supply curves will have a greater influence on the price compared to the quantity. Whilst, elastic supply curves will have a greater impact on the quantity rather than the price. Therefore, these are evaluative points that should be considered when analysing a supply curve shift.