Multilayer printed circuit board & Multi-layer pcb

Multilayer PCB consist of 3 or more circuit layers bonded together by a thickness of insulating material called prepreg and core. Multilayer printed circuit boards are most complicated than others, and are generally considered to be the most sophisticated PCB product due to their construction methods and design complexities.
These are a few of the applications using multilayer printed circuit boards:
● Communications
● Industrial controls
● GPS technology
● Aerospace
● Computers
● Military
● Medical
● Satellite systems