Why is my dishwasher backing up and how can I fix it?

Your dishwasher may be backing up due to a clog in the drain hose or pump, a faulty drain valve, or a problem with the garbage disposal. To fix it, try cleaning the drain hose and pump, checking the drain valve for any obstructions, and ensuring the garbage disposal is working properly. If the issue persists, you may need to call a professional plumber for further assistance.