Operator error A mistake made by a computer user. 
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Power failure A complete loss of power to the computer system. 
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Power spike A sudden increase of power that lasts less than a millionth of a second. 
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Power surge A sudden increase of power that can last several seconds. 
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UPS (uninterruptible power supply) A device that contains a battery to provide a continuous supply of power to a computer system in case of a power failure and contains circuitry to protect a computer from power spikes and surges. 
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MTBF (mean time between failures) A measurement of reliability that is applied to computer components. MTBF is derived by dividing the number of failures in test equipment by the total time they were tested. 
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Power strip A device that provides multiple outlets, but no protection for power surges and spikes. 
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Surge strip A device that protects computer equipment from electrical spikes and surges (also called a surge suppressor or surge protector). 
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Crackers People who break into a computer sys- tem with intent to damage files or steal data. 
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Cyberpunks People who break into computers, especially Internet computers, to steal data, modify files, or plant viruses. 
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Hackers The term "hacker'once meant acomputer hobbyist and has also been used to describe a computer novice. In most contexts today, it means a person who has gained illegal access into a computer system. 
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Computer virus A program designed to attach itself to a file, reproduce, and spread from one file to another, destroying data, displaying an irritating message, or otherwise disrupting computer operations. 
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File virus A computer virus that infects executable files, that is programs with exe filename extensions. 
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Payload The disruptive instructions or message delivered by a computer virus. Payloads can range from just being annoying to destroying data and files on a computer system. 
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Boot sector virus A computer virus that infects the sectors on a disk that contain the data a computer uses during the boot process. The virus spreads every time the infected disk is in the computer when it boots. 
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Macro A small set of instructions that automate a task. Typically, a macro is created by performing the task once and recording the steps. Whenever the macro is played back, the steps are repeated. 
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Macro virus A computer virus that infects the macros that are attached to documents and spreadsheets.
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Trojan horse A computer program that appears to perform one function while actually doing some- thing else, such as inserting a virus into a computer system or stealing a password. 
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Logic bomb A computer program that is triggered by the appearance or disappearance of specific data (for example, when the word "terminated" appears in an employee's record or when a pass- word begins with the letters "DB"). 
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Time bomb A type of computer program that stays in a computer system undetected until it is triggered at a certain date or time. 
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Y2K bug A time bomb unintentionally created by programmers when they wrote programs that used a two-digit field for the year, with the result that computers will read the digits 00 as 1900 rather than as 2000. 
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Worm A software program designed to enter a computer system, usually a network, through security "holes" and replicate itself. 
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Antivirus software A computer program used to scan a computer's memory and disks to identify, isolate, and eliminate viruses. 
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Checksum A value, calculated by combining all the bytes in a file, that is used by virus detection programs to identify whether any bytes have been altered. 
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Virus signature The unique computer code contained in a virus that helps in its identification. Antivirus software searches for known virus signatures to identify a virus. 
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Data security Techniques that provide protection for data. 
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Risk management The process of weighing threats to computer data against the expendability of that data and the cost of protecting it. 
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Acceptable use policy A set of rules and regulations that specify how a computer system should be used and set the penalties for misuse. 
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End-user procedures A set of formalized steps that a person must follow to perform a computing task.
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Biometrics Biological measurements, such as fingerprinting, that are used in the context of computers to verify a person's identity. 
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Trap door A way to bypass the normal security precautions and enter a computer system. A trap door is often created during computer installation and testing, but should be removed before the computer is placed into service. 
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User rights Rules that specify the directories and files that an individual user can access. 
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Encryption The process of scrambling or hiding information so that it cannot be understood with- out the key necessary to change it back into its original form. 
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Key In the context of data encryption, a key is the method used to encrypt or decipher information as in which numbers in a code match each letter of the alphabet. 
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Pretty Good Privacy (PGP) A popular public key encryption system. 
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Public key encryption (PKE) An encryption method that uses a pair of keys, a public key (known to everyone) that encrypts the message, and a private key (known only to the recipient) that decrypts it. 
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Digital certificate A security method that identifies the author of an ActiveX control. A computer programmer can "sign" a digital certificate after being approved. 
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Firewall A method for preventing hostile pro- grams, such as Java applets, from entering a net- work, usually by installing firewall software that filters out suspicious packets. 
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Java applet Small programs that add processing and interactive capabilities to Web pages. 
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Sandbox A metaphor for the limited areas and equipment that a Java applet can access on a computer. 
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Cookie A message sent from a Web server to a browser and stored on a user's hard disk, usually containing information about the user. 
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5-HTTP (Secure HTTP) A method of encrypting data transmitted between a computer and a Web server by encrypting individual packets of data as they are transmitted. 
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SSL (Secure Sockets Layer) A security protocol that uses encryption to establish a secure connection between a computer and a Web server. 
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Downtime Time during which a computer system is not functioning. 
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Hardware redundancy Maintaining equipment that duplicates the functions of equipment critical to computing activities. 
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Backup A backup is a duplicate copy of a file, disk, or tape. Also refers to a Windows utility that allows you to create and restore backups. 
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Copy disk A utility program that duplicates the contents of an entire floppy disk. 
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Copy utility A program that copies one or more files. 
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Backup software The software used to specify the folders and files that should be included when making a backup of hard disk data. 
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Full backup A copy of all the files on a disk. 
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Differential backup A copy of all the files that have changed since the last full backup of a disk. 
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Incremental backup A copy of the files that have changed since the last backup. 
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