(1) The authorization of access to data in a network, which is controlled by the network administrator.  Users are assigned an ID and password that allows them access to information and programs within their authority.  See 
authentication.  See also 
computer security and 
information security.
(2) Protecting the computer systems in the network from unwanted intrusions.  See 
UTM, 
firewall, 
antivirus program, 
network security scanner, 
IDS, 
IPS and 
SIEM.