What is the purpose of crankset spacers and how do they affect the performance of a bicycle?

Crankset spacers are used to adjust the chainline and spacing of the crankset on a bicycle. They help ensure proper alignment of the chain with the gears, which can improve shifting performance and reduce wear on the drivetrain components. Additionally, crankset spacers can also help fine-tune the overall performance and efficiency of the bike by optimizing the chain's engagement with the gears.