Definition:
A monitoring service will typically keep a constant eye on specific accounts. These are frequently associated with one specific Consumer Reporting Agency, or CRA. (FYI, CRA can also stand for Credit Reporting Authority.)
There are two types of CRAs, those that collect information covered by the Fair Consumer Reporting Act (FCRA), and those that collect information not covered by FCRA. The FCRA information is collected by Equifax, Experian, and TransUnion. Non-FCRA information is collected by LexisNexis and Acxiom.
Identity thieves have been known to trade information on the Internet through chat rooms. Some monitoring services scan these chat rooms for your information as well, however there are drawbacks to some scanning methods.
