Tell a real warning from a picture of one

Tell a message from your own computer apart from a picture of one on a web page — and know the single message that always deserves a yes.

A red page fills the screen. A countdown, a beeping noise, a telephone number for support. It is one of the most frightening things that happens online, and it is a picture.

There is one question, and it settles every case: is this coming from my device, or from a page in my browser? A web page can draw anything at all, including a perfect copy of a Windows warning. What it cannot do is know anything whatever about your computer.

Key points

What to remember

Try this

Check that automatic updates are switched on. Windows: Settings, then Windows Update. Mac: System Settings, General, Software Update. Phone: Settings, then Software Update.

Practice: Tell a real warning from a picture of one. Your first lesson is free, with no account or card; the rest are part of a Lantern plan. Interactive lessons require JavaScript.

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