In order to prevent building a board inside out, we must be able to identify the correct orientation of your design. Component, layer 1, or 'top' layer should read in facing up. All other layers should line up as though looking through the board from the topside.

The primary side of a printed board upon which the major of component parts are mounted. Where size allows, the component side may be printed with the ‘legend’. (Also see ‘ topside’)

A traditional single sided (S/S) pcb has an obvious component side. This is the side components are placed with their legs through component holes to be soldered to pads on the track side.