App Links are links that take people to an app or to specific app content. Specifically, App Links can refer to either Android App Links or Facebook App Links, which are specific deep linking standards used by one of those platforms.
It’s important to note that in order to take advantage of App Links you must have a live, functional mobile website.
App Links originally were introduced to replicate the functionality of iOS Universal Links, and effectively introduce a simple way to turn website links into links for mobile apps that are more useful for browsing mobile users. Therefore, if a normal HTTP/HTTPS link is clicked and the corresponding app is installed, it will open immediately. If the app is not installed, a provided fallback web link will trigger.