Design + Code an Android App from Scratch
This video talks about FragmentManager which is an interface for interacting with Fragment objects inside of an Activity and FragmentTransaction which is an API for performing a set of Fragment operations. FragmentManager tracks a list of Fragments in the current Activity. Each Fragment can be assigned an ID or a TAG which can be used by the FragmentManager later to find it using the findFragmentById or findFragmentByTag methods. FragmentTransactions let you add, remove, replace or hide Fragments in Activities programmatically.