According to a today's Yahoo press release, over 500 million user accounts were compromised in 21014 by what Yahoo is referring to as "state-sponsored" event.

There was speculation of a breach involving 200 million Yahoo accounts earlier this year, but this number is significantly larger.

To put that into perspective 500 million user accounts is more than the population of the United States, Mexico, 2and Canada - combined.

The account information that was taken included, personal names, phone numbers, email address, hashed user passwords and both encrypted and unencrypted security questions.

Yahoo is taking steps to invalidate the user passwords and security questions, however, this will not help you on any other sites in which you have used that combination. So, if you have issued the same email, passwords and "favorite pet" on other accounts, you change them now.

This would also be a good time to review or recent Password Management article as well as check out the cache of Password Managers tools we offer in our files listing.

Yahoo does not say what "state-sponsored" country they suspect or why it took them two years to notify customers.