Facebook has just announced their new mobile initiative on Android, called Facebook Home.

After much speculation from the tech press predicting anything from a Facebook phone to just an update to their existing mobile app, the real deal seems to be something in the middle: a mix of new applications that work on top of any standard Android installation.

I’ve seen a lot of confusion online over what Facebook Home actually is, especially because users more familiar with other platforms doesn’t really know how the Android ecosystem works. Obviously I’m not a Facebook employee, and I have no additional information on this project other than what’s publicly known, but as an Android user and developer, I figured I’d try clearing some of that confusion out.

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First, Facebook mentions Home is a family of apps. This should be a big enough clue on what the project actually is: a group of applications that, when used together, create a completely different experience on Android phones. How those applications operate is probably what’s hard to comprehend to non-Android users, or even some more casual Android users: one can easily replace core applications of the Android system, and in Facebook’s case, it seems they’re choosing to replace the system’s lock screen, launcher, and messenger apps.

On Android phones, the lock screen is the screen that shows when you first turn on your phone. On stock Androids, that shows you the time, gives you the option to unlock your phone, and on most recent versions of Android (4.2), allows you to switch to a number of lock screen widgets (called “daydream”) where you can perform certain tasks without unlocking your phone.

The interesting part is that like many other things on Android, you can completely replace the lock screen with a third party-application (with no unlocking or rooting required). And, of course, a plethora of third-party lock screen applications can be found on Google Play.

As such, Facebook is introducing their own lock screen called Cover Feed.

What Cover Feed does is replace the traditional lock screen with direct access to your normal Facebook stream, as well a list of the messages you receive on your phone. A privacy concern for many, I’m sure, but a great solution for users that use their mobile device as a Facebook device.

Some kind of unlocking gesture is probably available on that screen too. Doing so would take users to the phone’s application desktop, something called a launcher on the Android ecosystem (much like the lock screen, anyone can install a third-party launcher on their Android device, and sure enough, many such apps exist).

Facebook Home calls their launcher simply App Launcher.

The app launcher doesn’t get a lot of screen time both on Home’s launch video and on the website, but it seems to be a standard, icon-based launcher – you select which applications to see and where, and can launch them. Interestingly, you can perform Facebook actions – such as posting a status or a photo – straight from the launcher interface, which reinforces the idea that your phone is now a Facebook device.

Widgets – a powerful Android feature – are surprisingly absent from the custom launcher preview screens, which leads me to believe Facebook doesn’t want people to use them. A bold move, if true.

Finally, an integral part of the new Facebook Home seems to be their messaging application, apparently called Chat Heads.

This seems to be a mix of the user’s friends’ list with the system messenger – which can also, guess what, be replaced by third party apps. The interesting thing about this application, from my point of view, is how well it integrates with the rest of the system as a whole: rather than adopting the standard Android notification system for messages, where new messages are queued up on the notifications bar, new messages float on screen, on top of your current application. This is a feature that I know is available for Android apps, but I’ve rarely seem it used – it can be very intrusive. If done well, this is probably the best justification for the feature.

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Given what I’ve observed, I believe Facebook Home is just a group of applications designed to work together in transforming the user’s phone into a Facebook device; I haven’t seem anything that indicates a custom Android build or system-level hooks (it seems to use at least one custom system hook on HTC First). Still, they just seem to be a group of beautifully well designed apps that take advantage of what the Android system offers best, as well as their interoperability, to transform a device into the ultimate Facebook client.

In my opinion, that’s the perfect solution for a platform like Facebook. The more I think about it, the more it makes sense. Rather than announcing a proprietary Facebook phone – where they would ultimately have to deal with carriers, and risk fragmenting the Android system even more – they are simply announcing a collection of applications that are supposed to run on any Android device, without artificial, bureaucracy-driven constraints. While I’m sure Facebook Home won’t be available on every Android phone – they do mention a few specific devices on their website, and they’re helping HTC ship one of their new phones with the applications bundled – it wouldn’t make a lot of sense for them to outright block users out of their new playground. They probably have system requirements in place, however; I personally believe Home will only be available on Android 4 and above, perhaps Android 4.1.

Obviously, the whole privacy discussion is a huge topic in itself, but one that is beyond the scope of this post.

For Android developers, interestingly, Facebook Home is great news. While I know I won’t install any of these applications (I don’t even have the standard Facebook app on my Galaxy Nexus), I expect a move like this to motivate some social media consumers to finally upgrade their phones. Maybe that’s just wishful thinking, but personally, I can’t wait to see Android 4+ becoming the standard on the platform.

Update (April 05): differently from my first impressions, apparently Facebook Home does have system-level hooks on HTC’s new phone, the HTC First. At least one custom system API is provided to the application: the one that makes Android notifications available to the Facebook’s Cover Feed, so it can display any system notification on its lock screen (instead of just messages). This is not a showstopping feature that would prevent Cover Feed from being used in other, non-customized devices, but it raises one interesting point: it shows Facebook is not afraid to request custom functionality from phone manufacturers, and fork Android somewhat. Whether this is good or not in the long run is another matter; developers are not happy. I’m pretty sure Facebook has other priorities in mind, however, and I can see this application being successful with its target audience regardless.

Still, Android’s feature history is also one of convergence and adoption of new ideas first proposed by manufacturers with their own custom OS chrome. If the new hooks provided to Facebook Home by HTC’s phone turn out to be a good idea, I can only see them being rolled into an official system API in the future.