- The measures taken to protect a computer, the information contained within it, or that which it exchanges with other computers. Protection from eavesdropping or unauthorized access may be afforded, for instance, by passwords and encryption. Other modes of protection include biometric techniques, such as retinal scans, which determine if access is granted to a system.
- A security system which incorporates computers. A computer combined with a camera may be used, for example, to monitor the ingress and egress of motor vehicles through a property.