A change in supply is best described as a shift of the supply curve to the left or to the right. A shift in the supply curve means that at each given price, the quantity supplied by producers changes. This can occur due to various factors such as changes in production costs, technology, taxes, subsidies, or the number of producers in the market. A movement along the supply curve, on the other hand, occurs due to a change in the price of the good, which causes a change in the quantity supplied, but not a shift in the supply curve.