A modular structure in cybersecurity refers to a system design where different components, or modules, each perform a specific function independently. This approach allows for greater flexibility, easier updates, and improved resilience. If one module fails or is compromised, the rest of the system can often continue to operate, making it harder for attackers to disrupt the entire operation. Modular structures are commonly used in malware, security software, and network architectures to enhance adaptability and security.