What Economies of scale?

Reduction in cost per unit resulting from increased production, realized through operational efficiencies. Economies of scale can be accomplished because as production increases, the cost of producing each additional unit falls.

Economy of scale refers to things costing less per unit if many units are ordered. This happens for many reasons such as lower transportation costs per unit (orders come by truckloads and shiploads), tooling can be made and processes refined for larger production numbers, etc.