What is a printed circuit board?

A printed circuit board is basically used to mechanically support while at the same time electrically connecting electronic components by using conductive pathways. The process is very simple.
motherboard is a printed circuit ,where all components of the system is connected.
Printed circuit boards are used in nearly all electronic devices.
The conducting wires that connect all the components, are printed onto an insulating plastic material such as paxolin or fiberglass. These tracks are commonly made of thin copper sheet stuck to the board. The tracks are then printed using light and a chemical process to remove the unwanted copper.
Some boards used in remote controls and wafer thin boards used in ipods etc, are commonly printed, using conductive ink containing silver or carbon.

The alternative to printed circuits was to idividually wire the coponents using wire and solder tags. Old tube radios were originally wired this way, but had to be made by hand.
Printed circuits allow for automation and mass soldering using a float soldering process on a bed of molten solder.