What is the purpose of shims in carpentry?

Shims play a crucial role in carpentry, primarily serving to support and level structures. They are thin pieces of material, often made of wood or plastic, that can be inserted under or between objects to ensure that surfaces are even and aligned correctly. This is especially important in situations where surfaces are not perfectly flat or where adjustments are needed to achieve the desired alignment of doors, windows, cabinets, or other fixtures.

Using shims can help prevent structural issues that arise from uneven surfaces and can provide a more stable and aesthetically pleasing final result. For instance, if a door frame is not plumb, shimming can help to adjust it so that the door hangs straight, allowing it to open and close properly. The effectiveness of shims in ensuring level and stable installations makes them an essential tool in carpentry work.