Basics of Regular Expressions
A regular expression is a way of specifying a pattern in a text string. For example, if you specify the pattern
webpage
NetTracker would find any instance of webpage in the field you were searching. It would match webpage, awebpage, webpage1, and Here is a webpage.
To cite a more useful example from NetTracker, you can use regular expressions to generate a report on all the requests for HTM and HTML files on your site. Enter the filter that match the pattern htm in the Included Pages option in NetTracker. This will give you a report on any page that had htm in its file name. Assuming you had not used htm as anything other than a file extension, you would get a complete report on all the requests for HTML files on your site. This report would also include requests for files ending with html because the string html includes the string htm.
Note: This assumes that either all your file names have lowercase extensions or that you have not enabled case-sensitivity in your profile options. (When case-sensitivity is not enabled, all pages are imported as all lowercase characters. For details on enabling case-sensitivity, see "Enabling Case-Sensitivity for Pages".)