Would it surprise you to learn that millions of computers in the US are infected with malware? That's a lot of computers. So what's malware, and why should you care?

Malware, short for malicious software, includes viruses and spyware that get installed on your computer or mobile device without you knowing it. Criminals use malware to steal personal information and commit fraud. For example, they may use malware to steal the login information for your online accounts or to hijack your computer and use it to send spam. An infected computer can lead to serious problems, like identity theft.

The good news, there's a lot you can do to protect yourself and your computer. One of the most important steps you can take, install security software from a reliable company and set it to update automatically. The bad guys constantly develop new ways to attack your computer, so your software must be up to date to work.

Set your operating system and your web browser to update automatically too. If you're not sure how, use the help function and search for automatic updates. Don't buy security software in response to unexpected calls or messages, especially if they say they scanned your computer and found malware. Scammers send messages like these to trick you into buying worthless software, or worse, downloading malware.
What else can you do? Use a pop up blocker, and don't click on links and popups. Don't click on links or open attachments in emails unless you know what they are, even if the emails seem to be from friends or family.

Download software only from websites you know and trust. Free stuff may sound appealing, but free downloads can hide malware. Make sure your web browser's security setting is high enough to detect unauthorized downloads. For example, use at least the medium security setting.
Even if you take precautions, malware can find its way onto your computer. So be on the lookout for these signs. Your computer runs slowly, drains its battery quickly, displays unexpected errors or crashes, it won't shutdown or restart, it serves a lot of popups, takes you to web pages you didn't visit, changes your home page, or creates new icons or toolbars without your permission.

If you suspect malware, stop doing things that require passwords or personal info, such as online shopping or banking. Use a different computer, maybe one at work or at your local library, to change your passwords. Update your security software and run a system scan. Delete files it flags as malware.
If you can't fix the problem on your own, get help from a professional. Your computer manufacturer or internet service provider may offer free tech support. If not, contact a company or retail store that provides tech support.

Keep in mind, the most important thing you can do to prevent malware is to keep your computer software up to date. And remember, it's easy to find trusted information about computer security. Just visit onguardonline.gov, the federal government site to help you stay safe, secure, and responsible online.