Windows Defender Guide


Windows Defender is a free application that helps you stay productive by protecting your computer against pop-up windows, slow performance, and security threats caused by spyware and other potentially unwanted software. This application provides advanced system scanning and spyware removal technologies that simplify the removal of spyware on your system. Real-time protection helps prevent new spyware from installing while a streamlined alert mechanism minimizes interruptions. To help you make informed removal decisions, Microsoft analysts provide relevant information and guidance with each alert. From installation to maintenance, Windows Defender is easy to use and comes with pre-configured settings designed to help you stay secure.

This is a preliminary document and might be changed substantially prior to final commercial release of the software described herein.

About Spyware

Spyware is a general term used for software that performs certain behaviors such as advertising, collecting personal information, or changing the configuration of your computer. In general, this is done without appropriately obtaining your consent. You might have spyware or other unwanted software on your computer if:

  • You see pop-up advertisements even when you are not on the Web.
  • Either your home page or your browser search settings have changed without your knowledge.
  • You notice a new toolbar in your browser that you did not want and find it difficult to remove.
  • Your computer takes longer than usual to complete certain tasks.
  • Your computer is crashing often.

Spyware is often associated with software that displays advertisements, called adware or software that tracks personal or sensitive information. This does not mean all software that generates ads or tracks your online activity is bad. For example, you might sign up for a free music service, but "pay" for the service by agreeing to receive targeted ads. You might also agree to let the company track your online activities so they can determine which ads to show you. If you decided that this is a fair tradeoff, understand the terms, and agree to them, then this activity is ok.

Other kinds of unwanted software will make changes to your computer that can cause your computer to slow down or crash. These programs have the ability to change your home page or search page, or add unnecessary components to your browser. They also make it very difficult to change settings back to what they were originally set to. These types of unwanted programs are also often called spyware.

The critical factor is whether you or someone who uses your computer understands what the software will do and has agreed to install it.

There are a number of ways spyware or other unwanted software can get on to a system. Often this software is installed covertly during the installation of other intentional software such as a music or video file sharing program. Whenever installing something on your computer, carefully read all disclosures, including the license agreement and privacy statement. Sometimes the inclusion of unwanted software in a given software installation is documented, but it might appear at the end of a license agreement or privacy statement.

In order for Windows users to make informed decisions about what software to install and use, Microsoft believes that they should know the following:

  • All software running on the computer
  • Purpose of the software
  • How the software was installed
  • How the software was invoked
  • How the software can be blocked, disabled, or removed

As an industry leader, Microsoft is committed to addressing spyware and other potentially unwanted software concerns. Microsoft Windows Defender is a key component of the Microsoft anti-spyware strategy. For more information on spyware and a detailed overview of Microsoft's strategy, see Spyware Solutions: Technology and Leadership at: