Every so often, new breaks of a security breach at some large-scale organization, and 'Pwned Passwords' is a new service that helps people to adjust after such a potentially dangerous occurence. The service, which is part of online security awareness site 'Have I Been Pwned,' checks words against it online database of over 306 million publicly available leaked passwords, giving users an idea of whether their passwords might have ended up in a breach.
As reports of data breaches continue to roll in, people are becoming increasingly savvy with online security. The problem with these reports, though, is that it's basically impossible for someone to definitely know if their own information was compromised. Though Pwned Passwords can't say for sure who the entered password belongs to, it will at least show users if their password was involved in a leak (either from their own account or from someone else using the same one.)