A massive data breach at National Public Data has compromised the personal information of billions of Americans, including Social Security numbers, prompting alarms over identity theft. Estimates of those affected range from 1.3 million to as high as 2.9 billion, with the data now circulating on the dark web. Consumers are urged to protect themselves by using tools like the one launched by Pentester, which allows individuals to check if their information was involved in the breach. Experts recommend freezing credit with major bureaus to prevent unauthorized accounts from being opened and to monitor financial activities closely. The breach highlights the need for increased vigilance regarding personal information sharing and security practices.