Reference

Cybersecurity glossary

Concise definitions for common security and privacy terms. Each definition notes important limits where a marketing shorthand could be misleading.

Antivirus: Software that detects, blocks and removes malicious or unwanted software. Modern products also commonly filter dangerous websites.
Encryption: A mathematical process that transforms readable information so that only someone with the correct key can recover it.
Firewall: A control that permits or blocks network connections according to rules. A firewall does not inspect every kind of harmful content.
Malware: The broad term for malicious software, including ransomware, spyware, trojans and computer worms.
Multifactor authentication (MFA): Account protection requiring more than one factor, such as a password plus a security key, passkey or authenticator.
Passkey: A phishing-resistant sign-in credential based on public-key cryptography, unlocked with the user's device or password manager.
Password manager: An encrypted vault that generates, stores and fills unique credentials. Its security also depends on the account and recovery setup.
Phishing: A social-engineering attack that impersonates a trusted person or organisation to steal information, money or account access.
Ransomware: Malware that encrypts data or disrupts systems and demands payment. Some groups also threaten to publish stolen information.
Social engineering: Manipulation that exploits trust, urgency, fear or authority to persuade a person to weaken security.
VPN: A virtual private network encrypts traffic between a device and a VPN server and replaces the public IP seen by destination services.
Zero-knowledge architecture: A design intended to prevent a service provider from accessing decrypted customer data. The exact guarantees depend on implementation.
Adware: Software that injects advertising, changes search results or redirects pages. It is usually installed alongside free downloads or browser extensions.
Botnet: A network of compromised devices controlled remotely and used for spam, fraud, credential attacks or denial-of-service traffic.
Brute-force attack: An automated attempt to guess a password or key by trying many combinations. Long, unique passwords and rate limiting make it impractical.
Credential stuffing: Using username and password pairs leaked from one breach to log in elsewhere. It works only when passwords are reused.
Data breach: An incident in which personal or business information is accessed or copied without authorisation. Exposed data is often resold for later attacks.
DNS: The system that translates a domain name into a network address. A hostile or misconfigured resolver can send you to the wrong destination.
End-to-end encryption: Encryption in which only the communicating parties can read the content, not the service carrying it.
Exploit: Code or a technique that takes advantage of a software flaw. Prompt updates remove most exploited flaws from consumer devices.
HTTPS: Encrypted web traffic between browser and site. It protects data in transit but does not prove the site is the company it imitates.
Identity theft: Fraudulent use of someone's personal details to open accounts, obtain credit or impersonate them with an organisation.
IP address: The public network address a device presents online. It reveals an approximate location and internet provider, not a personal identity.
Keylogger: Malware or hardware that records keystrokes to capture passwords, card numbers and messages.
Kill switch: A VPN feature that blocks internet traffic if the encrypted tunnel drops, preventing accidental exposure of the real connection.
No-logs policy: A provider's claim that it does not record user activity. Its value depends on independent audits, jurisdiction and technical design.
One-time code (OTP): A short code valid briefly for a single login. Codes can be phished in real time, so passkeys are stronger where available.
Patch: A software update that fixes a defect or security flaw. Enabling automatic updates is one of the highest-value security habits.
Password entropy: A measure of how unpredictable a password is. Length and randomness raise entropy far more than substituting symbols for letters.
Pharming: Redirecting a correct web address to a fraudulent server, typically by tampering with DNS settings or a router.
Sandbox: An isolated environment where a program runs with limited access, so suspicious code cannot easily affect the wider system.
SIM swap: Fraudulent transfer of a phone number to an attacker's SIM, allowing interception of text-message codes and account resets.
Smishing: Phishing delivered by text message or messaging apps, often using a shortened link and a short delivery or banking pretext.
Spyware: Software that secretly monitors activity, location, messages or credentials, sometimes installed by someone with physical device access.
Trojan: Malware disguised as legitimate software. Cracked applications and fake installers are the most common delivery route.
Two-factor authentication (2FA): A specific form of multifactor authentication combining a password with one additional factor such as an app code or security key.
Vishing: Voice phishing by telephone, frequently impersonating a bank, a technical support desk or a public authority.
WPA3: The current Wi-Fi security standard. Use it, or WPA2 as a minimum, with a long router password on home networks.
Zero-day: A vulnerability exploited before a fix exists. Layered defences and rapid patching limit the window of exposure.