Open your PC and look at the motherboard for an example of a mutilayer PCB.
Just look at the recommended breakout pattern for any 1000 pin BGA and you'll understand that multilayer PCBs are mandatory if you want to use even a fraction of the pins of such a device.
The examples of multilayer PCB in our day to day life is mother board of PC,Circuit board of your mobile phone, the PCB of USB storage device, Also may be the PCB available in Washing machine (But not quite sure). If could open up anyone and have a look.
Open your PC and look at the motherboard for an example of a mutilayer PCB.
Just look at the recommended breakout pattern for any 1000 pin BGA and you'll understand that multilayer PCBs are mandatory if you want to use even a fraction of the pins of such a device.