Nikon D3200 AE-L/AF-L Button: If you prefer your subject to be off-center, press this button to focus on your subject in the center of the frame. This allows your camera to keep them in focus when you position them.
Nikon D3200 Beginner DSLR: Guided Tour
Nikon D3200 Guided Tour: everything you need to know if you are considering or have recently purchased the D3200
What is Shutter Speed? Photography Tutorial #BACKTOBASICS