Probably it's time to change your passwords again, or to finally add two-factor authentication to your account. Security researchers have discovered a huge database of login credentials from over 560 million accounts (email addresses and passwords).
The database was discovered by the Kromtech Security Research Center, which provided the information with Troy Hunt. 
Most of the information is already on Hunt's "Have I Peened" website, which allows users to see if their accounts have been leaked in previous data breaches.
This means that most of the information contained on this database was gathered during our known violations on websites such as: LinkedIn, LastFM, Tumblr, and Dropbox.
So, if you have not yet changed your password when the violation was announced on any of these sites, now is definitely the time to do so.
No one knows who created the huge database of data.
