All web pages are overlaid with adverts – even those where you don’t expect to see adverts, such as Wikipedia.

You find any web searches are unexpectedly redirected away from your usual search engine to some site you’ve never heard of (or the results appear in a page that’s faked up to look like your usual search engine).

Typically these toolbars claim to make it easier to search or shop.

You find there’s a new toolbar in your browser that you didn’t install.

Your Mac suddenly becomes sluggish or laggy in everyday use, as if there’s some software running in the background chewing up resources.

Here are some of the symptoms of malware or viruses you might watch out for: One is the stringent protections Apple builds into macOS, another is the fact that it is exceptionally difficult for a virus to propagate itself and spread to other Macs, see: Why Macs are more secure than Windows PCs. Mac malware is incredibly rare – Mac viruses do exist, in fact there have been a few notable malware and virus reports in recent years, but there are a few reasons why Mac viruses don’t tend to take hold. It’s not necessarily the case that a virus is to blame though.

These are all signs that you might have a virus on your Mac. Another sign is the sudden appearance of annoying pop-up windows or extra toolbars and applications you don’t remember installing. If your Mac has suddenly become very slow and laggy, started regularly crashing or showing error messages, and the sound of your fans whirring keeps you company, you may be suspicious that you have picked up some Mac malware. Get Deal How to tell if your Mac has a virus

Malware antivirus for mac