While Quora.com isn't hugely popular this side of the world, you will still stumbled upon the site while Googling for answers to random questions.
However, it says account and user information such as name, email, IP, user ID, encrypted password, user account settings, personalisation data, public actions and content including drafts, data imported from linked networks you've authorised and non-public actions like answer requests and downvotes were compromised.
Hashed passwords are passwords stored in a site's database that are encrypted so that they aren't stored in human-readable plain text form.
Quora, like many sites today, offer the option to log in with a Google or Facebook account, which may have been the "linked networks" that their blog is referring to.
Quora first realised it had been compromised on Friday and immediately began investigating. Quora has also sent out an email to all affected users, detailing the breach, as well as next steps required to be taken to protect their accounts from being compromised.
"We believe we've identified the root cause and taken steps to address the issue, although our investigation is ongoing and we'll continue to make security improvements", D'Angelo wrote.
Questions and answers written anonymously were not affected, as Quora explained that they don't store identities of people who post anonymous content.
The company said it was working to notify affected users, and that it was logging out all those who may have been affected "out of an abundance of caution".
Quora has set up a help center on this link.
But don't worry, your identity probably won't be stolen because Quora doesn't collect sensitive personal information like credit card or social security numbers.
The company will now notify users whose data has been compromised, and will invalidate passwords for users who use one to sign in.