Data Controller Notification Requirements (UK vs US): In the UK, data controllers must notify their data subjects of data security breaches that pose a high risk to individuals' rights and freedoms, according to the General Data Protection Regulation (GDPR). Notification should occur "without undue delay" and, where feasible, within 72 hours of the breach being discovered. In the US, there is no single federal law mandating data breach notification. Instead, notification requirements vary by state, with different laws governing when and how individuals must be notified of breaches. The Largest Data Breach of the 21st Century: The largest data breach occurred with Yahoo in August 2013, which was discovered and publicly disclosed in December 2016. Data breach details include: Number of Records Stolen : 3 billion user accounts Type of Data Exposed : Usernames, email addresses, hashed passwords, and security questions and answers Method of Atta...