A shim is a wedge-shaped object typically made of wood that is used to space or level materials. It is a useful tool in construction projects and woodworking. Shims come in various sizes and materials, and they can be custom-cut to fit specific needs. Cedar is a popular material for wooden shims, although plastic shims are also available. Some plastic shims have the advantage of being splinter-free and less prone to splitting. Shims are often used to level cabinets or furniture, as well as to adjust the alignment of doors during installation.