A chip package that contains two ball grid array (BGA) chips. A package on package (PoP) typically includes a RAM chip on top and a CPU chip on the bottom. See BGA
and chip package
A 3D Package
The top BGA package typically contains RAM, which can also be a multi-die module itself, while the bottom BGA holds the logic chip (the processor). The light green elements are the BGA substrates. The PCB is the printed circuit board.