Online buying and selling is almost as old as the Internet itself.  eCommerce companies such as Amazon and eBay are true pioneers and their successes are undisputed.  Many other sites, dedicated to buying and selling have followed – focused on specific product categories and brands — launch every day.  A significant number of them have associated mobile apps; although most were specifically designed for the desktop, with mobile as an afterthought.  Increasingly, eCommerce sites now utilize Responsive Web Design (RWD) – those that provide an optimal user interface experience, regardless of the display type from mobile to desktop. In virtually all cases, mobile was an add-on – in other words, the site, product, or brand, first builds their online presence and the mobile views are added later.