A type of malicious code that is designed to make and distribute copies of itself. Like biological viruses, computer viruses insinuate themselves into legitimate programs and reproduce when those programs are run. Viruses often have a payload that can trigger functions that may range from merely annoying (flashing joke messages) to destructive ones that destroy crucial data. Even harmless viruses can cause problems by consuming memory or tying up processor power.
VPN or Virtual Private Network
A network that has characteristics of a private network such as a LAN, but which is built upon public network such as the Internet. VPNs allow organizations to implement private networks between geographically separate offices and remote or mobile employees by means of encryption and tunneling protocols.
A flaw in software programming that allows attackers to gain unauthorized access into a computer and perform actions such as viewing, appropriating or modifying data, or launching denial of service attacks. So called because their existence makes the program or software vulnerable to attack.