Organizations use these to check if their users' credentials have been compromised in third-party breaches.

This designation suggests the list has been cleaned of duplicates, syntax errors, and "junk" data. It often implies a high hit rate on popular services.

Testing credentials against various platforms to find account matches.

Update credentials for sensitive accounts immediately.

Use Multi-Factor Authentication to provide a layer of security that a simple password cannot bypass.

Use services like Have I Been Pwned to see if your email appears in known datasets.