App Linking is an open standard to deep link to content in your app. When someone using your app shares content to Facebook or another App Linking enabled app you can create a link that makes it possible to jump back into your app from that piece of content. App Linking work by adding metadata to existing URLs on the web so that they can be consumed by your app.

The Facebook's app for iOS and Android support App Linking today. When the Facebook app comes across a link that supports App Links it will launch your app with the right information so someone can see the content immediately and quickly