There are two kind of wildcards, one is (*), the other is (?). (*) stands for any number of characters
(?)stands for one character. and they are case-insensitive.
*.txt matchs aaa.txt and bbb.txt
a?.txt matchs aa.txt and ab.txt
Regular Expressions allow to search complex patterns of words. it looks a bit hard for novices, but
it's really simple and powerful.