Currently, users can chat through the Messages tab located on the bottom toolbar in the main Facebook app, but that tab will soon redirect users to download the Messenger app instead. When installed, a message received in the Facebook app will switch the user over to Messenger to chat, as it does now when a user has both the Facebook and Facebook Messenger apps installed.
According to TechCrunch, Facebook is making the switch so that it does not have to support two versions of Messenger, thereby improving both apps. Facebook gave TechCrunch an official statement on the upcoming changes:
In the next few days, we're continuing to notify more people that if they want to send and receive Facebook messages, they'll need to download the Messenger app. As we've said, our goal is to focus development efforts on making Messenger the best mobile messaging experience possible and avoid the confusion of having separate Facebook mobile messaging experiences. Messenger is used by more than 200 million people every month, and we'll keep working to make it an even more engaging way to connect with people.Facebook has already forced users in Europe to switch over to Facebook Messenger to send and accept messages.
Facebook for iOS can be downloaded from the App Store for free. [Direct Link]
Facebook Messenger for iOS can be downloaded from the App Store for free. [Direct Link]