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What is antivirus?

Antivirus software looks for viruses and other malicious software on a computer or laptop, and is meant to detect and remove them. The NCSC says it is important to use antivirus software and keep it up to date. Antivirus software is often included in the operating systems that run Windows and Apple computers. 1

By Secordit. Last checked: 10 November 2026.

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How it works

  1. If the built-in antivirus on a Windows or Apple computer is switched on, the NCSC says you will be safer. Keep it up to date. Modern products can apply updates on their own. 1
  2. New computers often come with a trial of a separate product. When the trial ends you may have to pay or register to keep using it. Separate products will not always work alongside the built-in tool and can stop it working. 1
  3. For a first use, the NCSC says to run a full scan and set the product to scan new files, including downloads and removable media. Also set it to receive updates when they are issued. 1

How it can look

A new laptop arrives with a trial of a separate antivirus product already installed. When the trial ends, a message asks you to pay or register. The NCSC warns that a separate product will not always work alongside the built-in tool and can stop it working. 1

Warning signs

  • The built-in antivirus is switched off, out of date, or has been replaced by a trial that may clash with it. 1
  • A product asks you to pay or register after a trial ends, and you are not sure whether the built-in tool is still working. 1
  • A phone or tablet is being used to install apps from outside the usual app stores, such as Google Play and the Apple App Store. 1

What to do now

  1. On a Windows or Apple computer, switch on the built-in antivirus, which the NCSC says is often included, and keep it updated. The NCSC says switching it on makes you safer. A trial third-party product may not work alongside the built-in tool, and could stop it working. 1
  2. Run a full scan, and set the product to scan new files, including downloads and removable media. Also set it to receive updates when they are issued. 1
  3. On a smartphone or tablet, the NCSC says you do not need a separate antivirus product. That applies if you only install apps from stores such as Google Play and the Apple App Store. Also set apps and the device to apply updates when they are offered. 1

UK reporting and support

How to protect yourself

  • Keep the built-in antivirus switched on and updated on a Windows or Apple computer. A trial add-on can clash with it. 1
  • On phones and tablets, install apps only from stores such as Google Play and the Apple App Store. Set apps and the device to apply updates when they are offered. 1
  • Apply software updates, and be careful with unexpected downloads. See also malware and tech support scams. 12

Frequently asked questions

Do I need to buy antivirus software for my Windows PC or my phone?

On a Windows or Apple computer, the NCSC says you will be safer if the built-in antivirus is switched on and kept up to date. A trial add-on can clash with that built-in tool. On a smartphone or tablet, the NCSC says you do not need a separate antivirus product. That applies if you only install apps from stores such as Google Play and the Apple App Store. Also set apps and the device to apply updates when they are offered. 1

What should I do the first time I use an antivirus product?

The NCSC says to run a full scan and set the product to scan new files, including downloads and removable media. Also set it to receive updates when they are issued. 1

Is antivirus the same as malware?

No. Malware is the harmful software. Antivirus is the built-in or add-on tool that looks for it. The malware glossary page covers the harm in more detail. 1

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Sources

  1. NCSC, What is an antivirus product? Do I need one?. Accessed 10 November 2026 (Europe/London).
  2. NCSC, Protecting your devices. Accessed 10 November 2026 (Europe/London).
  3. NCSC, Help for individuals. Accessed 10 November 2026 (Europe/London).
  4. Report Fraud, Report Fraud. Accessed 10 November 2026 (Europe/London).
  5. Report Fraud, Guide to reporting cyber crime and fraud. Accessed 10 November 2026 (Europe/London).
  6. Police Scotland, How to report a crime - Police Scotland. Accessed 10 November 2026 (Europe/London).
  7. Report Fraud, Reporting cyber crime and fraud or phishing attempts - Report Fraud. Accessed 10 November 2026 (Europe/London).