I know this service -
https://haveibeenpwned.com - has been posted before; but if you've signed up for email alerts there's a good chance you've just received something like this:
In essence, the guy who runs this site (
a respected security researcher - so don't feel too concerned about inputting your email address on the website.) has just imported another
458,000,000 email address/password combinations - so nearly half a billion compromised accounts.
Worryingly, this was part of a list that gets sold to people to "
credential stuff"; i.e try on random websites and applications. More frustratingly, despite the fact it's an aggregation, 26% of the combinations haven't been previously reported - so it's impossible to determine who was hacked and what information was compromised.
Seriously, pop your email address(es) in to that site and register for alerts for any accounts you use regularly; it's a massive step to boosting your defence. On top of that, no one can miraculously remember unique passwords, so do yourself a favour and look in to password managers.