Pallets started out as skids. Pallets like much everything else were invented out of necessity. Before wooden pallets, cardboard boxes and simple  wood skids were used. At  some point in the 1920’s, someone figured out that if you took a wooden skid and added some stringers with an additional platform the result was a far  more durable shipping option. WWII introduced the 4-way  pallets as a more secure transport means for war supplies. They have not changed much since their original design. Today there are literally billions of pallets in circulation both 2-way, Stringer designs and 4-way block designs. They are found in every warehouse around the globe and across every supply chain. These humble  tools have  revolutionized how supply chains operate and how good are stored and delivered.