JMeter comes bundled with a Regular Expression Extractor component that gives you fine-grained control over what to extract from a server response using regular expression syntax. Readers familiar with regular expression syntax will feel right at home, but don't worry if you haven't used regular expressions before. Regular expressions are special characters that match portions of a field based on a set of rules defined by a regular expression pattern. More information about regular expressions can be found on http://en.wikipedia.org/wiki/Regular_expression or by searching on the Internet.