More than a million people are accessing Facebook through Tor, an anonymity tool used to evade surveillance.
The social networking giant confirmed the news Friday after more than two years in operation. The company introduced access to Tor in October 2014, allowing users who use the service to communicate directly with Facebook's datacenters.
Facebook was one of the first major websites to operate on the Tor network. What made the implementation more interesting was the addition of HTTPS, which added another layer of encryption, making access to the site more secure.
Tor allows people to access the "dark web," which are underground sites that can't generally be accessed through the ordinary internet.
Though the dark web has negative connotations for hosting black market sites, drug forums, and other illegal marketplaces, many use the Tor network to access ordinary websites but with a layer of protection to prevent prying outside eyes.
That's not only useful to criminals, but also ordinary citizens who aren't afforded the freedoms and protections that many Westerners have, or by journalists to communicate with sources, or by anyone who puts a premium on their privacy.
In some regions, like China and Russia where state surveillance is rife, using Tor is one of the few ways to access Western services.
"It's important to us to provide methods for people to use our services securely -- particularly if they lack reliable methods to do so," said Alec Muffett, a software engineer for security infrastructure at Facebook.