Is your login secure?

Following a string of revelations from several media companies who announced they had been recently hacked, Twitter came forward this past week to say it had also been the target of a sophisticated attack. Anonymous hackers breached the social network and may have gained access to passwords and other information for as many as 250,000 user accounts. Twitter said in a blog post that the passwords were encrypted and that it had already reset them as a "precautionary measure," and that it had notified affected users.

Password hacking and identity theft has become an all too frequent headline in today's world of online communities. While Twitter scrambles to amend its breach, the site can take solace in the knowledge that it's not the only popular web service to have been compromised. Here are the stories behind other recent password violations of the Internet's most used sites.

Watch: More on the recent Twitter attack