The term social commerce was introduced by Yahoo! in November 2005 to describe a set of online collaborative shopping tools such as shared pick lists, user ratings and other user-generated content sharing of online product information and advice [55]. Stephen and Toubia [47] defined social commerce as a form of Internet-based social media that allows people to actively participate in the marketing and selling of products and services in online marketplaces and communities. Marsden [33] summarized social commerce as a subset of electronic commerce that involves using social media, online media that supports social interaction and user contributions, to assist in the online buying and selling of products and services. From this definition, we note that there are two key aspects - social interaction and user contributions - for social commerce, which are derived from social media characteristics.