Introduction Electronic commerce, or commerce taking place via electronic communication media, ranges from the traditional electronic data interchanges on closed networks and commerce via fax or telex, to the modern forms of online commerce via the web, email, and mobile phones. The focus of this chapter is on the latter, and in particular the online selling and buying of goods and services, as opposed to the provision of ancillary services to enable internet access, retrieve data, or host material. The spectrum of the goods or services sold online is wide, encompassing goods and services delivered physically, as well as the new digital intangible goods, such as fi lms, music, software, books, news, fi nancial data, and pornography; and services, such as online banking, internet telephony, or the provision of recreational activities, such as gambling and gaming in virtual worlds. In these latter instances, the contract is not only made, but also performed, electronically. The vast majority of these online transactions are relatively low-value business-to-consumer (B2C) or consumer-to-consumer (C2C) transactions (for example, eBay transactions) rather than business-to-business (B2B) transactions, and so the legal protection of consumers forms a central part of the regulatory landscape.