IT security glossary


Spy program that inspects the sites visited by a user to display targeted ads as pop-ups or banners.


Software protection against viruses.


The operation of collecting and classifying computer data


A confidential and secure access point to an operating system, program or online service. 
A backdoor also refers to small programs in a computer installed (usually by worms) unbeknownst the user, giving it access to computer control.


An operation which duplicates and secures the data in a computer system. The backup always involves data recording, but not necessarily for the purpose of archiving.


Rate of information flow of a device (such as memory, hard disk, and so on) or of a communication medium (network, bus, etc.) or ingeneral any rate of information flow, such as that between the processor and the memory cache.

Computer archive

An archive is a file in which the whole folder content is located (files, arborescence and access rights). Archives are usually files with the .Tar (UNIX format) or .Zip (Windows) addon and they are often compressed.
An archive is aimed at transporting an entire folder into one file.
To compress data and create archives proprietary software such as WinZip or WinRAR for Windows is often used. But there is also some free software such as free IZArc and 7-Zip.

Computer data

Information used by software. It can be created by a user or generated by the program itself.

Computer system

A set of equipment for the automatic processing of information: recording, editing, deletion and retrieval of information


Text file created in a hard disk to store the web pages visited by the user. 
A cookie remembers passwords, IDs, configurations, etc.

Differential backup

A backup method which involves copying only the data changed since the last full backup.

Disk space

Storage capacity available on a magnetic disk.


Software system for protecting a machine against intrusions from the network. The firewall acts as a filter on the information exchanged.

Hacker or hackers

Person or people who generally use information and communication technology maliciously to penetrate protected computer systems in order to harm or to retrieve data.

Hard Drive (HDD)

Mass magnetic storage mainly used in computers, but also indigital music players, camcorders, DVD players / recorders, video game consoles, personal digital assistants and mobile phones.


Fraudulent e-mail comprising false information that urges therecipient to perform actions harmful to the machine’s security and which propagates this information to as many people as possible.

Incremental Backup

Backup on a selective principle in which only new data created since the last backup operation is copied.


Software recorder of computer activities which stores the computer keys used by its victim.


All malicious programs introduced on a computer unbeknownst to the user.


A computer hardware used to interconnect all the components of a computer.


Fraudulent technology for obtaining personal information: birth date, credit card numbers, passwords, etc.


Ads that appear in front of the web page being viewed by a user.


A software component located between two others to assist or to monitor their exchanges.
In computer networks more particularly, a proxy is used as an intermediary program to access another network, typically the Internet.

RAID (Redundant Array of Independent Disk)

Techniques to distribute data across multiple hard drives in order to improve fault tolerance, safety or performance of the whole.

RAM (Random Access Memory)

Random access memory or volatile memory is computer memory in which a computer puts data when processing it. 


Malicious code that attaches itself to an operating kernel and maintains real-time fraudulent access to a computer system which is already compromised.


Hardware or software placed on a network to listen and to retrieve sensitive information without the knowledge of users or network administrators.


Mass shipment of e-mails, often advertising, to non-consenting recipients that clogs up mailboxes and mail servers.


Unhealthy intrusive software aimed at spying on Internet browsing habits of the user and to deduce its market needs for commercial purposes.


Operation which stores data without duplicating them or classifying them.

Trojan or Trojan horse

A malicious program that allows total intrusion into a computer virtually undetected by the victim and takes remote control of it.

VPN (Virtual Private Network)

A private extended area network established by creating permanent dedicated links between business networks through public networks in order to meet the resource-sharing needs of its users.


Small malicious program that fits into a legitimate computer program and infects it so that it can reproduce itself through it. Today, most viruses are worms.


Level of exposure to IT threats.


Intrusive parasite program which nibbles a computer system’s resources: memory, bandwidth, etc.. A worm may act as a virus spreading from machine to machine or as a spy. It can also saturate a website, destroy data, etc.