Network design involves creating and specifying the architecture of a network, which includes its hardware, software, protocols, and communication technologies. The goal is to devise a system that can effectively transmit data, provide requisite services, and support future growth. Effective network design balances performance metrics, security requirements, and budget constraints while complying with relevant regulations. It requires an understanding of network topologies, the types of networks (LAN, WAN, etc.), and considerations for redundancy and failover.