Security glossary

Plain definitions for the 24 terms that appear most often on security product pages — written so you can read a vendor's feature list and know what it is claiming.

Adware

Software that displays advertising you did not ask for, often bundled with a free program. Not always technically malicious, but frequently unwanted and sometimes a vehicle for worse.

Behaviour analysis

Detection based on what a running program does rather than on what file it is. Can catch previously unknown malware; can also misjudge legitimate software.

Botnet

A network of compromised machines controlled remotely and used collectively — for sending spam, for distributed attacks, or for renting out to others.

Command and control (C2)

The server infrastructure malware contacts after installation to receive instructions. Blocking these connections is one of the things a firewall and a reputation service try to do.

Cryptojacking

Malware that quietly uses your machine's processor to mine cryptocurrency. Rarely destructive; noticeable as unexplained slowness, heat and fan noise.

Definition / signature

A fingerprint of a known-malicious file — a hash or a characteristic byte pattern. The basis of traditional scanning, useless against anything not yet catalogued.

Exploit

Code that takes advantage of a specific flaw in software to make it do something it should not. Patching removes the flaw and so removes the exploit.

False positive

Legitimate software wrongly flagged as malicious. Measured separately by testing laboratories because an over-eager product is its own kind of problem.

Firewall

A component that decides which network connections into and out of a machine are permitted. Modern operating systems include one; suites usually add their own with more granular rules.

Heuristics

Rules of thumb that flag files or behaviour resembling known malware without requiring an exact match. The predecessor of, and often bundled with, behaviour analysis.

Keylogger

Software that records what you type, usually in order to capture passwords and card details.

Malware

The umbrella term for any software written to do harm — viruses, worms, trojans, ransomware, spyware and the rest.

Phishing

Fraud that persuades a person to hand over credentials or money, typically through a message and a convincing imitation of a real login page. It attacks the person, not the software.

Ransomware

Malware that encrypts your files and demands payment for the key. The stage at which it is interrupted determines how much is lost; after encryption completes, only a backup helps.

Real-time protection

Scanning that happens as files are created, opened or run, rather than only during a scheduled scan.

Rootkit

Malware that modifies the operating system to hide its own presence, which makes it difficult to detect from inside the running system.

Sandbox

An isolated environment in which a suspicious program can be run and observed without giving it access to the real system.

Social engineering

Manipulating a person into taking an action — approving a payment, granting remote access, reading out a code. It defeats security software because the action is genuinely taken by the genuine user.

Spyware

Software that collects information about you and sends it elsewhere without your knowledge.

Trojan

Malware disguised as something legitimate — a cracked application, a document, an installer — that you run yourself.

Two-factor authentication (2FA)

Requiring a second proof of identity in addition to a password. The single most effective thing most people can do for account security, and entirely outside the scope of an antivirus product.

Virus

Strictly, malware that attaches itself to another file in order to spread. In everyday use, a loose synonym for malware generally.

Worm

Malware that copies itself across a network without needing anyone to open anything.

Zero-day

A vulnerability, or an attack using one, for which no patch exists yet. Detection here depends on behaviour analysis rather than signatures, because there is nothing catalogued to match.

Compiled by Oliver Young for DELTA BARS s.r.o., published 25 September 2026. Definitions are written for a general reader; where a term is used differently by a particular vendor, that vendor's documentation prevails. Spotted an error? info@coratis.online.