The Deep Web, designed as a vast expanse of the internet that search engines can't wrap their robotic heads around. One of the final frontiers of Earth in some ways, the land of bitcoin, secret forums and .onion links is powered by a privacy algorithm known as TOR. Recently cracked by the feds but still considered viable for most security purposes, TOR has been in wide use for many purposes for quite some time. Though some still use it for nefarious deeds, it has garnered a reputation among crowds from privacy-minded individuals to businesses as being reliable, but slow. Despite the standard having been around for quite some time, the TOR bandwagon is still rolling strong. In 2014, Facebook jumped on that bandwagon and made their own .onion site, which proved quite popular. Today, it was announced that they're adding official support for TOR to their Android app.
Those familiar with TOR probably know of the Orbot app for Android that allows you to filter some, if not most, of your phone's network traffic through TOR. Up until now, using TOR this way with Facebook required going through the browser and the .onion website or some rather hacky workarounds. With this newest update, however, users can set up Orbot, fire it up and check the relevant option in the Facebook app and they'll be good to go. Some options that would require exiting the secure TOR network, such as push notifications, will be disabled. The setting should be rolling out slowly in updates, so if you haven't gotten it yet, don't fret, the rollout is still going as of this writing.
The new feature is great for those accessing Facebook in insecure environments or needing extra protection for any other reasons. Some users simply prefer to use TOR at all times and this newest change will make it much easier for them to use the Facebook app. Thus far, there is no word of any release for iOS or other platforms, though Facebook does "commonly receive requests for additional platform support", so TOR support for other platforms may be coming in the near future.