What is meant by the term "network security"?

Network security refers to the protective measures implemented to guard a computer network against unauthorized access, attacks, and various threats that can compromise data integrity or confidentiality. The main goal of network security is to ensure that the data traveling across the network remains secure and that the network users can safely connect and interact without falls prey to cybercriminals.

When considering the provided choice, it correctly defines network security by focusing on the protection aspect, which encompasses various strategies and tools such as firewalls, intrusion detection systems, and secure ports to prevent intruders from exploiting vulnerabilities. This protection is paramount in securing sensitive information and maintaining trust in communications over the network.

In contrast, the other options do not encompass the full scope of what network security entails. The mention of online security of individual accounts pertains more to personal cybersecurity measures rather than a broader application of securing a network. Meanwhile, data encryption is an important element of security but is just one tactic among many used within network security. The sale of network components does not address the protective function needed to shield against threats but rather focuses on the commerce aspect of security solutions. Together, these factors illustrate why the selected answer effectively captures the essence of network security.