Networking and security
Network security is the practice of preventing and protecting against unauthorized intrusion into corporate networks.
As a philosophy, it complements endpoint security, which focuses on individual devices; network security instead focuses on how those devices interact, and on the connective tissue between them.
The venerable SANS Institute takes the definition of network security a bit farther
Network security is the process of taking physical and software preventative measures to protect the underlying networking infrastructure from unauthorized access, misuse, malfunction, modification, destruction, or improper disclosure, thereby creating a secure platform for computers, users, and programs to perform their permitted critical functions within a secure environment.