A contract proof usually serves as an agreement between customer and printer and as a color reference guide for adjusting the press before the final press run. Most contract proofs are a prepress proof. The primary goal of 'proofing' is to serve as a tool for customer verification that the entire job is accurate. Prepress proofing (also known as off-press proofing) is a cost-effective way of providing a visual copy without the expense of creating a press proof. If errors are found during the printing process on press, correcting them can prove very costly to one or both parties involved.