A regular expression, without surrounding characters. For example, a*b or ab|cd, not /a*b/.
This is a graph of the FSA that corresponds to this regular expression. This won't help you use
regular expressions; it's just to test my graph presentation library, and for fun. If you're interested in this sort of thing, see my reAnimator
For more information about how to use regular expressions, including examples, additional documentation, and additional tools, see: