# Cyber security glossary, in plain English.

> A plain-English glossary of cyber security terms, from phishing and ransomware to MFA, EDR, SOC, penetration testing and Cyber Essentials.

Canonical: https://cybersecuritylondon.com/cyber-security-glossary


By Cyber Security London, published 11 October 2026.

**In short:** Cyber security is full of jargon. This glossary explains the terms London businesses hear most often, from phishing and ransomware to MFA, EDR and penetration testing, in one or two plain-English sentences each.



## A to Z

- **Breach**: An incident where information is accessed, changed or lost without permission.
- **Cyber Essentials**: A UK government-backed certification covering five basic technical controls that protect against common attacks.
- **Cyber Essentials Plus**: The same five controls as Cyber Essentials, verified by hands-on technical testing.
- **Dark web monitoring**: A service that watches breach data and criminal markets for your company's details, such as staff passwords.
- **EDR**: Endpoint detection and response: software on laptops and servers that spots and stops suspicious behaviour.
- **Encryption**: Scrambling data so only someone with the right key can read it.
- **Firewall**: A barrier that controls which network traffic is allowed in and out.
- **Incident response**: The planned steps an organisation takes to contain, investigate and recover from a security incident.
- **ISO 27001**: The international standard for managing information security, which organisations can be certified against.
- **Malware**: Malicious software, such as viruses, spyware or ransomware.
- **MDR**: Managed detection and response: EDR plus a team that watches and responds to alerts 24/7.
- **MFA**: Multi-factor authentication: a second check, such as a code on your phone, on top of a password.
- **Patch**: A software update that fixes a security weakness.
- **Penetration test**: An authorised, simulated attack carried out by a person to find and prove weaknesses.
- **Phishing**: Emails or messages that trick people into clicking a link, opening a file or handing over details.
- **PCI DSS**: The security standard for organisations that take card payments.
- **Ransomware**: Malware that locks or steals your data and demands payment to release it.
- **Risk assessment**: A structured review of what could go wrong, how likely it is and how much harm it would cause.
- **SOC**: Security operations centre: a team that monitors systems and responds to threats.
- **SOC 2**: A US attestation report on how a service organisation protects customer data.
- **UK GDPR**: The UK's main data protection law, covering how organisations handle personal data.
- **Vulnerability**: A weakness in software, hardware or a process that an attacker could use.
- **Vulnerability scan**: An automated check for known weaknesses across your systems.
- **Zero-day**: A weakness that attackers know about before a fix is available.

## Frequently asked questions

### What is the difference between cyber security and information security?

Information security protects all of an organisation's information, digital or not. Cyber security is the part focused on digital systems, networks and data.

### What is the most common cyber attack on UK businesses?

Phishing. The UK government's Cyber Security Breaches Survey 2025 found it was experienced by 85% of businesses that identified a breach or attack.

## Sources

- [Cyber Security Breaches Survey 2025, Department for Science, Innovation and Technology](https://www.gov.uk/government/statistics/cyber-security-breaches-survey-2025/cyber-security-breaches-survey-2025)
- [Small Business Guide, National Cyber Security Centre](https://www.ncsc.gov.uk/collection/small-business-guide)

## How we can help

- [Security Awareness Training](https://cybersecuritylondon.com/security-awareness-training)
- [Cyber Security Assessments](https://cybersecuritylondon.com/cyber-security-assessments)

## Contact

Email letstalk@networklondon.co.uk or use the enquiry form at https://cybersecuritylondon.com/#contact. Cyber Security London, The Leather Market, London Bridge, London.