Definition
A security breach is an incident where unauthorized individuals gain access to sensitive, protected, or confidential data. This can involve the theft, alteration, or destruction of information, or the disruption of services. In practice, organizations implement robust security measures like firewalls, intrusion detection systems, and access controls to prevent such incidents. Understanding security breaches is crucial for protecting an organization's assets, maintaining customer trust, and ensuring regulatory compliance. For example, a phishing attack leading to the compromise of employee login credentials constitutes a security breach. Unlike a vulnerability, which is a weakness that *could* be exploited, a breach signifies that the exploitation has already occurred. This concept is fundamental to cybersecurity certifications such as CompTIA Security+, CySA+, and CISSP.