Q

QAZ Virus of 2000
Virus discovered in China in July 2000. It spread over a network through a back door, enabling a remote user to set up a connection to take control over someone's computer using port 7597. Because the virus could not be spread to machines outside the network, it may have been initially sent by email.

QT
Online abbreviation for "cutie."

quantum cryptography
An experimental method for securely transmitting encryption keys by using individual photons of polarized light.

quarantine
To isolate files, just as to quarantine sick persons means to isolate them from others in order to stop the spread of disease.

qubit
A quantum bit.

query language
A language used to express queries to be answered by a database system.

queue
A data structure from which items are removed in the same order in which they were entered.

quicksort
A sorting algorithm invented by C.A.R. Hoare and first published in 1962.

QuickTime
The standard way of storing digitized sound and video on the Macintosh.

quit
To clear an application program from memory.