In November and December of 2013, cyber-criminals breached the data security of Target, one of the largest U.S. retail chains, stealing the personal and financial information of millions of customers. On December 19, 2013, Target confirmed that some 40 million credit and debit card account numbers had been stolen. On January 10, 2014, Target announced that personal information, including the names, addresses, phone numbers, and email addresses of up to 70 million customers, was also stolen during the data breach. A report by the Senate Committee on Commerce in March 2014 concluded that Target missed opportunities to prevent the data breach. This book answers some frequently asked questions about the Target breach, including what is known to have happened in the breach, and what costs may result. It also examines some of the broader issues common to data breaches, including how the payment system works, how cybersecurity costs are shared and allocated within the payment system, who bears the losses in such breaches more generally, what emerging cybersecurity technologies may help prevent them, and what role the government could play in encouraging their adoption. The book addresses policy issues discussed in congressional hearings and describes some of the legislation that Congress has introduced to deal with these issues. This book also presents an explanation of how the Target breach occurred, based on media reports and expert analyses that have been published since Target publicly acknowledged this breach.