The efficiency of arguments can often be increased through the use of wildcards and other regular expressions . A wildcard is a character that is used to represent some category of character or characters in pattern matching. The wildcard with the broadest coverage and which is most commonly used is the asterisk ( * ), which stands for any combination of characters, including no characters. Its use eliminates the need to type in all the individual file names as arguments. Regular expressions are a powerful pattern matching technique that is widely used for searching for files and for data within files.