1. Introduction Network security is the practice of protecting a computer network from intruders, whether targeted attackers or opportunistic malware. Its primary goal is to ensure the confidentiality , integrity , and availability (the CIA triad) of data and resources. As organizations increasingly rely on cloud services, remote work, and IoT devices, network security has evolved from simple perimeter defense to a multi-layered, adaptive strategy. 2. Core Principles (The CIA Triad) | Principle | Description | Example | |-----------|-------------|---------| | Confidentiality | Ensuring data is accessible only to authorized parties. | Encryption, access control lists (ACLs). | | Integrity | Guaranteeing that data has not been altered by unauthorized means. | Hashing, digital signatures, checksums. | | Availability | Ensuring systems and data are accessible when needed. | Redundancy, DDoS protection, failover clusters. |