A security breach occurs when unauthorized individuals gain access to sensitive information or systems. This can happen through various methods, such as hacking, phishing, or exploiting software vulnerabilities. The compromised data may include personal information, financial records, or confidential business information, leading to potential harm for individuals and organizations. Organizations often implement security measures to protect against breaches, including firewalls, encryption, and employee training. However, even with these precautions, breaches can still occur, highlighting the importance of ongoing vigilance and response strategies. Notable examples of security breaches include incidents involving major companies like Equifax and Yahoo, which exposed millions of users' data.