Wild cards are used in searching for information by Application programs and operating systems in files or documents. Often the asterix (*) can be used as a wildcard and it represents any character you like. For example if you are looking through a list of names of Countries and you want only those containing the letter 'X' then you would search for '*X*' which denotes any letter(s) before the X and any letter(s) after. This would find both Luxembourg and Mexico.