By now you have read about the socalled Heartbleed bug which causes significant vulnerability to a number of websites and if infected can let attackers gain access to your password and trick you into using false websites.
The known affected sites include Yahoo, Google, Facebook, Netflix and Tumblr which have announced that the problem on their sites has been fixed, but users should change their passwords. In is yet to be known whether personal data is in any way compromised.
To understand the size of the potential problem