An issue that needs further consideration is the growth predicted by most authors for digitised products. Digitized products are characterised by increasing returns to scale which is explained by the cost advantages of using the Internet: the cost of the first copy or download is very high but the marginal cost of additional copies is very low or nil. On the other hand, goods and services that can be bought and sold via the Internet but are transported by traditional mechanisms are characterised by diminishing returns to scale due to the costs they incur (tariffs, custom surcharges, consumption taxes etc.)/the marginal cost of reproduction is relatively higher.