What is the function of a sander in wood finishing?

A sander is an essential tool in wood finishing primarily used for smoothing surfaces and preparing them for finishing treatments such as stain, varnish, or paint. The sander works by removing imperfections like roughness, scratches, or any uneven areas on the wood's surface, which helps achieve a smooth texture. This process is critical because a well-sanded surface ensures better adhesion of finishes and contributes to a more visually appealing final product.

While the application of paint or stain is indeed part of the finishing process, that function is not the role of the sander. Similarly, joining pieces of wood and measuring and marking them are tasks associated with other carpentry tools and methods, rather than the purpose of sanding.