What is "android-fragment"
A Fragment represents a behavior or a portion of an interface in a Actvity. You can combine multiple Fragment's in a single Activity to build composite interfaces (multi-pane), and reuse a Fragment in multiple Activities.
You may think that a Fragment is a modular section of a Activity, which has its own life cycle, receives the data entry events themselves, and which you can add or remove while a Activity is running (a kind of "sub Activity" which you can reuse in different Activities).
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