Unless you have worked with regular expressions before, the term and the concept may be unfamiliar to you. However, they may not be as unfamiliar as you think.
Think about how you search for files on your hard disk. You most likely use the ? and * characters to help find the files you're looking for. The ? character matches a single character in a file name, while the * matches zero or more characters. A pattern such as 'data?.dat' would find the following files:
Using the * character instead of the ? character expands the number of files found. 'data*.dat' matches all of the following:
While this method of searching for files can certainly be useful, it is also very limited. The limited ability of the ? and * wildcard characters give you an idea of what regular expressions can do, but regular expressions are much more powerful and flexible.