Where malware comes from
Malware most commonly gets access to your device through the Internet and via email, though it can also get access through hacked websites, game demos, music files, toolbars, software, free subscriptions, or anything else you download from the web onto a device which is not protected with anti-malware software.
How to recognize malware
A slow computer is often a sign that your device may be infected with malware, as are pop-ups, spam, and frequent crashes. You can use a malware scanner (which is included in all malware removal tools) to check if your device is infected.