Facebook Messenger (Communication and News)
You might wonder why you'd need a messaging app in addition to the official Facebook app on your smartphone. The answer: You can use Facebook Messenger for Android, BlackBerry, and iPhone to send time- and location-stamped messages to groups of your Facebook friends--and it works faster than SMS or email.
The app also logs your chats inside Facebook, whether you use your phone or your desktop PC. You can send new photos, photos you've saved on your phone, or images that you find using Bing search.
Even people who don't use smartphones can reply to messages, simply by confirming their mobile phone number to activate Facebook texts.