Solder mask is a protective layer applied to printed circuit boards (PCBs) to prevent solder from bridging between conductive paths. It is typically made from a polymer material and is usually green, although other colors are available. This layer helps to ensure that solder only adheres to designated areas, improving the reliability and performance of the electronic components. In addition to preventing solder shorts, solder mask also protects the PCB from environmental factors like moisture and dust. It enhances the durability of the board and can improve its appearance. Proper application of solder mask is crucial for the overall quality of electronic devices.