What is Data breach?
When a company's systems are broken into and customer data — emails, passwords, card numbers — is stolen or exposed.
Breaches happen to companies of every size and are usually not your fault. What matters is your response: change the affected password everywhere you reused it, enable two-factor authentication, watch for breach-themed phishing, and alert your bank if payment data was involved. Free services like haveibeenpwned.com tell you when your email appears in known breaches.