Computer security tips: a checklist for your Windows PC or Mac

Windows and macOS both ship with antivirus, a firewall, encryption and backup tools. Most security problems on home computers come from those being switched off, out of date or never set up. Work through this list once — it takes well under an hour — and then let automatic updates do most of the work.

1. Turn on automatic updates

• Windows 11: Start > Settings > Windows Update > Check for Windows updates, then Download & install. Microsoft recommends turning on automatic updates to keep Windows, Office and other Microsoft apps current.
• Windows 10: Microsoft stopped providing free security fixes for Windows 10 after October 14, 2025. A Windows 10 PC no longer gets them through Windows Update.
• Mac: Apple menu > System Settings > General > Software Update, and turn on automatic updates there.
• Update everything else too — your browser and other apps.

2. Keep the built-in protection on

• Windows Security is built into Windows and provides real-time malware detection, prevention and removal. Windows' firewall is built in and turned on automatically.
• macOS includes XProtect, built-in antivirus that checks for updates daily by default, plus Gatekeeper and notarisation, which block untrusted software.
• On a Mac, check the firewall at Apple menu > System Settings > Network > Firewall.
• Run one real-time antivirus at a time. On Windows, Microsoft Defender steps aside automatically when you install another one.

3. Use a standard account day to day

Both Microsoft and Apple recommend doing everyday work in a standard, non-administrator account and keeping administrator accounts to a minimum. Malware that runs in a standard account can't change as much of the system. Give each person in the house their own login.

4. Lock the screen

Press Windows logo key + L on Windows, or Control + Command + Q on a Mac, to lock the screen when you step away, and require a password when the computer wakes from sleep or the screen saver.

5. Encrypt the disk

• Windows: Device encryption turns on automatically when you sign in with a Microsoft account, including on Windows Home; with a local account it isn't turned on automatically. Check under Settings > Privacy & security > Device encryption. Full BitLocker management comes with Pro, Enterprise and Education.
• Mac: Macs with Apple silicon or a T2 chip encrypt your data automatically. FileVault adds the requirement to log in with your password to unlock it — Apple menu > System Settings > Privacy & Security > FileVault. Keep your recovery key safe: if you lose both your password and the key, the data is gone.

6. Back up

• Mac: Time Machine (Apple menu > System Settings > General > Time Machine > Add Backup Disk) keeps hourly, daily and weekly backups on an external drive. Apple suggests a drive at least twice your Mac's storage.
• Windows: Windows Backup syncs your folders to OneDrive; a free Microsoft account includes 5 GB. It's a sync of your files, not a full image of the PC.
• Follow the 3-2-1 rule — three copies, in at least two places, with at least one offline — so ransomware or a dead drive can't take everything.

7. Passwords and two-factor authentication

• Use long passwords — the US FTC suggests at least 15 characters — or let a password manager generate them, and don't reuse them across accounts.
• Turn on two-factor authentication. Codes by text or email are the most common; an authenticator app or a security key is more secure.

8. Be choosy about downloads and links

• Install software only from the vendor's official website or the app store, and avoid software from untrusted sources.
• Don't click links in unexpected emails or texts. Contact the company through a phone number or website you know is real.

9. Secure your Wi-Fi router

• Use WPA3 Personal or WPA2 Personal encryption; WPA and WEP are outdated.
• Change the router's default admin username and password, and the network name.
• Keep the router's software updated.
• Turn off remote management, WPS and UPnP, and turn on the router's firewall.
• Put visitors on a guest network.

10. Public Wi-Fi: less scary than it used to be

Because most websites now use encryption, connecting through a public Wi-Fi network is usually safe, the US FTC says — check for https in the address bar on sites where you enter personal information. A VPN adds privacy on networks you don't trust, but it's an extra, not a requirement.

Do you need paid antivirus too?

For one well-kept computer, the built-in protection covers the core job. A paid suite adds cover for the household's other devices from one account, warnings about scam and phishing sites, and extras such as a VPN or password manager. Our guide to whether Windows Defender is enough walks through the trade-offs.

The best security settings are the ones already on your computer. Switch them on, let them update, and keep one backup offline.