Huffpost Technology

As much as 66 percent of the Web may have been compromised by a newly revealed security flaw called Heartbleed.

So named by the researchers who discovered it, Heartbleed is a bug that affects an important internet security protocol called SSL. Specifically, it affects one particular implementation of SSL called OpenSSL.

For context (and to understand how bad Heartbleed is), here’s how SSL and OpenSSL work: Every time you log into a website, your login credentials are sent to that website’s server. But in most cases those credentials aren’t simply sent to the server in plain text — they’re encrypted using a protocol called Secure Sockets Layer, or SSL.