Business experts have enthusiastically projected a seamless, retail world where customers can shop across channels, anywhere and at any time. This type of multiple channel retailing is often referred to as Omni-Channel Retailing. Within academia, by contrast, there have been proportionately fewer attempts to systematically categorize the diversity of multiple channel retailing that currently exists. Hence, the concepts Multi-, Cross-, and Omni-Channel are used indistinctly. This article proposes a categorization of Multi-, Cross-, and Omni-Channel Retailing for retailers and retailing by means of a literature review, a taxonomy of multiple channel retailing, a literature classification table, and by way of illustration, a mobile Click and Collect shop.