Wildcards are like the blank pieces in Scrabble, or like the Jokers you can use in some card games to stand in for any card. You are perhaps already familiar with the “*” and “?” wildcards from file matching: In the File + Open dialog, you can display all files with the extension “.doc” by typing “*.doc”, or all files “01062001.doc”, “01072001.doc”, “01122001.doc”… by typing “01??2001.doc”.
But the wildcard feature in Word goes way beyond that, and can be very powerful.