What Is a Debt Collector?
Under the Fair Debt Collection Practices Act (FDCPA), a debt collector is generally any person or company that regularly collects debts owed to someone else, typically a third party working on behalf of, or having purchased debt from, an original creditor.

Third-Party Collectors vs. In-House Departments
Third-party collectors are separate companies contracted or sold debt by your original creditor, and they're the primary target of FDCPA protections. In-house collection departments, working directly for the original creditor, are generally treated differently under federal law and may not be covered by the same FDCPA rules, though many state laws add further protections.
What They Can and Can't Do
At a high level, collectors must follow rules on call timing, cannot harass or threaten you, and must honor your right to request written validation of the debt. See our full FDCPA page for the complete picture.
For example, a third-party collector generally can't call you before 8 a.m. or after 9 p.m. local time, can't call you at work once you've told them not to, and can't threaten legal action they don't actually intend to take. If a collector crosses these lines; you can report it to the CFPB or FTC, see our Consumer Rights guide for how to file a complaint.