Single-panel (Single-Sided Boards) on the most basic PCB, components concentrated in the side, wire centres on the other side (with SMD components and wires for a plug-in device to the other side). Because wires only occurs on one side, this PCB is called single-sided (Single-sided). Because a single panel in the design line there are many severe restrictions on (because only one side, wiring can't cross paths that must be around alone), so only the earlier circuit using such boards.
Double-sided boards (Double-Sided Boards) both sides of the circuit board and wiring, but you have to use both sides of the wire must have appropriate electrical connection lines in between the two sides. This "bridge" is called a pilot hole (via). Pilot hole is on the PCB, or coated metal-filled holes, it can work with both sides of the wire is connected. Because the double-sided Board 1 time times greater area than a single panel, double panel solved the staggered because of wiring difficulties of single-panel (you can pass to the other side by Kong Dao), it is more suitable for use in more complex than single-sided circuit.