[This version of Windows Defender is still in development, so some Help information might be inaccurate or missing.]

Spyware: frequently asked questions

Here are answers to some common questions about spyware.

What is spyware?

Spyware is software that can install itself or run on your computer without providing you with adequate notice, consent, or control. Spyware might not display symptoms after it infects your computer but many harmful or unwanted programs can affect how your computer runs. Spyware can, for example, monitor your online behavior or collect information about you (including personally identifiable or other sensitive information), change settings on your computer, or cause your computer to run slowly.

How can I tell if I have spyware or unwanted software on my computer?

You probably have some form of spyware on your computer if:

There might be spyware on your computer even if you don't see any symptoms. These types of software can collect information about you and your computer without your knowledge or consent. Running Windows Defender whenever you use your computer can help you find and remove such software.

Where does spyware and potentially unwanted software come from?

Unwanted software can be installed by websites, downloaded programs, or a program you might install from a CD, DVD, external hard disk, or a device. Spyware is most commonly installed through free software, such as file sharing, screen savers, or search toolbars.

Can I get spyware without knowing it?

Yes, some spyware can be installed from a website directly through an embedded script, or program in a webpage. Some unwanted software requires your help to install through web pop-ups or free software that require you to accept a downloadable file. However, if you keep Windows up to date and don't reduce your security settings, you can minimize the chances of a spyware infection.

What do I do when a pop-up won't close until I agree to install a program or change my home page?

Some websites will repeatedly display pop-ups asking you to install a toolbar or change your home page. When this happens, try closing the browser window. If the pop-ups still appear, right-click the Internet Explorer window button in the taskbar at the bottom of your screen, and then click Close Group. As a last resort, close any other programs you have open, and then restart your computer.

How can I prevent spyware?

Software products, such as Windows Defender, can protect your system by watching for spyware trying to install itself or run on your computer. Spyware protection programs can also scan your system automatically to find and remove spyware that might already be installed.

Keeping your Windows operating system up to date is also important. Microsoft often releases security updates to help prevent spyware from being installed without your knowledge. Most new antivirus programs have spyware protection, and should be kept up to date as well. We recommend that you turn on Automatic Updates for Windows, and that you update your spyware and antivirus programs regularly.

When you visit websites, do not automatically agree to download anything the site offers. If you download free software, such as file sharing programs or screen savers, read the license agreement carefully. Look for clauses where you must accept advertising and pop-ups from the company, or that the software will send certain information back to the software publisher. For more information about preventing spyware infections when you go online, go to the Microsoft Windows Defender website.

How do I remove unwanted software?

The best way to remove spyware is with an automated spyware protection program which scans for and removes potentially unwanted software from your computer. For more information about removing spyware and other unwanted software, see Using Windows Defender or Remove spyware from your computer.