Android NDK is a C++ library for Android phone.

NDK has functions to access the physical components of the phone, such as sensors.

NDK stands for Native Development Kit.

NDK can compile your C++ code.

NDK is used:
• to improve performance (because C++ is faster than Java)
• for manual memory management (C++ is manual memory management, Java is not manual)
    In Java, objects are deleted from memory automatically (the system Garbage Collection is used) and deleted after some time.
    In C++ we control when to remove the object and this is very effective.

Conclusion: NDK is used in games.
    In games, the scene is redrawn 30 times per second and a lot of heroes move, and you need speed and efficient memory management.
    Watch the video conference Google: "Google I/O 2009 - Writing Real-Time Games for Android"