adware — This is a type of malware (see malware definition below) that is designed to force the display of advertisements on the computer.

antivirus — This is a type of software that can detect some malware, not just viruses (see malware and virus below for an explanation of the difference).

back door — This is some form of unauthorized access to a computer system or network. For example, a "back door" might be a special user account, or special software designed to give access to a computer criminal.

bot — (short form of "robot") This is a type of malware that permits a computer criminal to have remote control of a computer (a.k.a. "back door"), to use it for e-mail spam distribution, or collecting data from it, or using it to attack Internet services.

client-server network — This is one method computers can use to connect to each other, in which a group of "server" computers hold the files to be shared, and "client" computers can connect to these servers to receive those files. Client-server networks are often used for e-mail delivery or web browsing. Compare to peer-to-peer network below.

data — As the word is used in this website, "data" will usually refer to any information that is stored on a computer or disk or memory card, and is intended for human use. Examples: documents, spreadsheets, e-mails, databases.

decryption — For an explanation of this term, see encryption below.

DNS — Domain Name Service (DNS) is a system of computers on the Internet that translates an easy-to-read Internet address into the numeric form that must be used to deliver data on the Internet. For example, DNS will translate the easily-recognized "www.sc.edu" address into the numeric address 129.252.189.62.

encryption — Data can be disguised in such a way that it can only be revealed by those who possess the appropriate secret key (or keys). The disguise process is called "encryption." The reveal process is called "decryption." See also encryption key.

encryption key or encryption factor — During the process of encryption, one or more items of public or secret information are used to encrypt data. Each of these items can be called an "encryption key" or "encryption factor." Examples: a password, a key file, a thumbprint (as read by a thumbprint scanner).

firewall — This is a type of software that attempts to prevent computers on the Internet from accessing the protected computer. Some firewall software will also attempt to prevent malware or spyware from reporting to the criminal, by limiting which programs on the protected computer are permitted access to the Internet. A firewall can also exist as hardware device that will provide some of this functionality to a network of computers.

hosts file — This is a file residing on a computer, overriding the DNS process (see DNS above). In most cases if an Internet address appears in the hosts file the computer will use the numeric address found there instead of using DNS.

key file — (read the entry on encryption before proceeding) This is a special type of file that can be used in the process of encryption or decryption. Key files are created once, as a pair of files: a "public key file," and a "private key file." The public key file is used to encrypt data, which can then only be decrypted using the matching private key file. Even the same public key that was used to encrypt the data cannot be used to decrypt it. Therefore the public key can be shared openly and used an unlimited number of times without revealing any previously encrypted data.

malware — This word is a short form of the term "malicious software." Malware is any type of program that is created with the intent to cause damage, to steal data, or to abuse resources. Malware can be classified into several categories: virus, worm, trojan horse, bot, adware, and spyware (all defined in this glossary); though in many cases an individual malware program will fall into two or more of these categories.

password or passphrase — This is a string of letters, numbers, and other symbols used as a secret to permit access to a computer or to encrypt data. A password/passphrase is considered to be "weak" if it is short (less than 8 characters) or is a dictionary word. Even a misspelled word, or a non-English word, or an obscure proper name is considered "weak" because computer criminals use specially crafted password-guessing dictionaries that include such words. A "strong" password will be at least 8 characters in length, and contain upper and lower case letters, or contain punctuation or other symbols.

peer-to-peer network or P2P — This is one method computers can use to connect to each other, in which all of the computers involved are treated as equals. Any computer in a peer-to-peer network can typically be used to send files to any other computer in the same network. Peer-to-peer networks are often used for anonymous file sharing. Compare to client-server network above.

phishing and spear-phishing — "Phishing" (pronounced like "fishing") is any communication intended to trick the recipient into disclosing secret or sensitive information, such as passwords, Social Security Numbers, user names, or bank account numbers. Most often this communication is done by e-mail. See our Threats page for examples of phishing e-mails. When a phishing attempt is targeted at a small group of people, rather than broadly distributed, this is called "spear-phishing."

social engineering — This refers to any psychological technique used to manipulate people into doing something they would not ordinarily do. Examples: 1) In an e-mail or on the telephone, a person may pose as someone in authority, to convince the recipient to give out secret information. This is called "phishing". 2) A hacker might drop a bot-infected flash drive in the parking lot of a high-security data facility, so that an employee with access to the facility will find it and use it on a computer inside, thereby giving the hacker a "back door" into the facility's network.

spyware — This is a type of malware that is designed to secretly collect a record of computer usage habits, and report that information back by Internet to a central database.

system tray — This is the part of the Windows Task Bar that usually displays the date and time, and a few miniature icons for access to some of the currently running programs.

task bar (in Windows operating systems) — This is the part of the Windows Desktop that contains the Start button, contains the System Tray, and shows the currently running programs.

trojan horse — This is a type of malware that spreads by posing as a desirable program or data file.

virus — By popular adoption this word is commonly used to mean "any bad software." But when used in a stricter, technical sense, "virus" only refers to a type of malware that spreads by attaching itself to other programs.

volume (file volume) — This is the collection of files stored under a particular drive letter (in Windows) or a file system (in Macintosh, Unix, and Linux). A file volume must be "mounted" in order to access it, although mounting normally occurs automatically.

worm — This is a type of malware that spreads by copying itself onto other computers, or disks, or memory cards.