There are two basic types of data mining: subject-based and pattern-based. A subject-based data mining application could be used to retrieve data that could help an agency analyst follow a particular lead. Pattern-based, or link analysis, can be used to look for suspicious behaviors through nonobvious associations or relationships between seemingly unconnected people or activities. For example, a pattern-based data mining analysis could identify two terrorists who use the same credit card to book flight or who share the same phone number.