Facebook Messenger logo for iOS & Android.
|Initial release||August 9, 2011|
184.108.40.206.42 (Android) (January 2, 2015[±]
Facebook Messenger is an instant messaging service and software application which provides text and voice communication. Integrated with Facebook's web-based Chat feature and built on the open MQTT protocol, Messenger lets Facebook users chat with friends both on mobile and on the main website.
Facebook reported in November 2014 that Facebook Messenger has reached 500 million users. David A. Marcus heads Facebook Messenger and had joined Facebook on invitation of Mark Zuckerberg, CEO of Facebook.
Messenger for Mobile
In December 2012, the Facebook Messenger app for Android in some regions (such as Australia, South Asia, Indonesia, South Africa, and Venezuela) added the ability to use Messenger without a Facebook account by simply using a name and phone number. These changes are intended to allow Facebook Messenger to compete against similar mobile messaging platforms such as WhatsApp as an alternative to text messaging. Later updates added the ability to use Facebook Messenger as a replacement text messaging client on Android, and added "Chat Heads", an overlay chat system originating from Facebook Home.
On July 3, 2014, a native Facebook Messenger app was released for iPad. It was specially designed for iPad rather than just running as an enlarged iPhone app. Messenger for iPad features a multi-window interface showing a list of threads and the current conversation at the same time. 
There is some controversy surrounding the permissions required to govern its functionality. Some of the permissions include such things as being able to send SMS messages, which may cost money.
Messenger for Desktop
Messenger for Windows Desktop
Messenger for Windows Desktop was officially released on March 5, 2012 for Windows 7 users. Testing on the software began among a limited beta tester group on November 21, 2011; however, a leaked link to the beta-stage software was publicly revealed to tech bloggers by Israeli blog TechIT. Facebook responded the same day by announcing the link's availability through its Help Center.
Among its features is a "ticker" similar in function to the sidebar of friend activity seen by Facebook website users. At the time of release, "chatting with multiple friends, video calling, limiting chat availability and editing settings" were not available through the software. A Mac OS X version was mentioned by Facebook developers as forthcoming.
Messenger for Firefox
- Facebook Inc.. "Facebook Messenger". Google Play. Google. Retrieved January 4, 2014.
- Facebook Inc.. "Facebook Messenger". App Store. Apple Inc. Retrieved November 20, 2014.
- Facebook Inc.. "Facebook Messenger". Windows Phone Store. Microsoft. Retrieved November 13, 2014.
- "Blackberry World - Facebook Messenger". Retrieved May 21, 2013.
- "Facebook Messenger on Windows and Firefox will be no more March 3". TechRadar. Retrieved 5 March 2014.
- Tsukayama, Hayley (January 17, 2013). "Facebook Messenger app change allows free calls via WiFi". The Washington Post. Retrieved March 3, 3013. Check date values in:
- Zhang, Lucy (August 12, 2011). "Building Facebook Messenger". Facebook Engineering. Facebook. Retrieved March 3, 2013.
- Facebook new Messenger service reaches 500 million users
- Why Facebook Has Entrusted Its Future to the CEO of PayPal
- Zhang, Lucy (October 19, 2011). "A Faster Way to Message on Mobile". The Facebook Blog. Facebook. Retrieved August 12, 2012.
- Geron, Tomio. "Facebook Messenger Takes On SMS, With No Account Needed". Forbes. Retrieved 6 December 2012.
- "Chat Heads come to Facebook Messenger for Android". The Verge. Retrieved 12 April 2013.
- "Facebook Messenger arrives for Windows Phone sans voice features". Engadget. Retrieved 5 March 2014.
- "Facebook Is Forcing All Users To Download Messenger By Ripping Chat Out Of Its Main Apps". TechCrunch. 2014-04-09. Retrieved 2014-05-29.
- "No more in-app chat: Facebook moving messages to Messenger". techhive. 2014-04-09. Retrieved 2014-05-29.
- "Facebook Messenger Finally Gets An iPad Version". TechCrunch. Retrieved 5 July 2014.
- Constine, Josh (March 5, 2012). "Facebook Messenger For Windows Desktop Chat Client Launches After Leaking". TechCrunch. AOL. Retrieved August 12, 2012.
- Constine, Josh (November 21, 2012). "Facebook Testing Messenger for Windows Ticker+Chat Desktop Client". TechCrunch. AOL. Retrieved August 12, 2012.
- אבי ,דוד (December 29, 2011). "בלעדי: Facebook Messenger עבור מערכת ההפעלה Windows להורדה". TechIT (in Hebrew). Retrieved August 12, 2012.
- O'Connor, Jack (March 5, 2012). "Introducing Messenger for Windows". Facebook Newsroom. Facebook. Retrieved August 12, 2012.
- Official website
- Facebook Messenger at iTunes Preview
- Facebook Messenger at the Google Play store
- Messenger on the Windows Phone Store.