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What are pop-ups, and how do I stop them?

Toast popping up out of a toaster

Small internet windows that pop up on your screen can be useful, annoying or dangerous – often used by advertisers to get your attention or by viruses to trick you into clicking on them. This guide gives basic information about some of the pitfalls and how to deal with them.

Jack Schofield | 9th September 2010

Pop-ups are small windows that ‘pop up’ over the top of web pages in your internet browser.

Advertisers used them as a way to get your attention, but users soon became annoyed, leading software providers and all the major web browsers to introduce pop-up blockers. As a result, some better uses for pop-ups - for example, to display helpful information or show videos - have been restricted.

Danger lurking beneath

Less trustworthy pop-ups try to get users to click on them. This is dangerous. A pop-up may include a button that says ‘Close’ or ‘Cancel’, but there is no guarantee that the link behind the button will dismisses the pop-up.

It could trigger another pop-up or download a virus. It’s safer to close a pop-up in Microsoft Windows by using a keyboard shortcut such as Ctrl-W or Alt-F4, or by opening the Task Manager, selecting the browser programme and clicking End Task.

Some pop-ups don’t come from websites but from malware (a malicious type of software) that has been secretly installed on the user’s PC. If this happens, the PC must be thoroughly cleaned using good security software. If the PC has been used to access banking, shopping and other important sites, all passwords should be changed because they may have been compromised.

Particularly nasty pop-ups are used to sell fake anti-virus programs, which are sometimes called ‘scareware’. The pop-ups pretend to find viruses on your PC and - after you have paid up - pretend to remove it. In fact, these programs are malware and may install more malware. For further details, see the Microsoft Security page called ‘Watch out for fake virus alerts’.

To stop pop-ups in Microsoft’s Internet Explorer 8, go to the Tools menu, select ‘Pop-up Blocker’ and then ‘Turn On Pop-up Blocker’.

To stop pop-ups in Mozilla’s Firefox, click on Tools, select ‘Options’, and then ‘Content’. Click the checkbox next to ‘Block Pop-up Windows’. Most browsers have similar options.

Pop-ups can be helpful

Not all pop-ups are there to infect your computer. On some sites they’re used to explain something so that you don’t have to navigate away from the main window. Also, sometimes pop-ups appear when you need to download or install something from a web page. Only ever interact with these pop-ups if you trust the website they’ve come from.

Jack Schofield

Jack Schofield

Jack Schofield is a technology journalist and blogger who covered IT for the Guardian from 1983 to 2010. Before specialising in computing, he edited a number of photography magazines and books.