Introduction To Windows Defender 

Older versions of Windows were known to be quite vulnerable to spyware and other malicious programs. Partly due to bugs, both in the operating systems and in the applications, and partly due to the widespread use of Windows, the number of these programs grew exponentially. Several solutions did appear -- but choosing one particular anti-spyware tool was quite difficult, with tens of such products available.

Windows Defender was released in 2006, under the name of Microsoft AntiSpyware. Since then, it has gathered so many users, that it now comes with Windows Vista, and is available as an optional download for Windows XP SP2 users. But how does Windows Defender help?

Essentially, Windows Defender has two modes of working. The first one is the
Automatic Scanning mode. By default, a quick scan for spyware is performed every night at 02:00. Of course, you have the option of scheduling the scans yourself. The other mode is the Real-time protection mode. Windows Defender will continuously monitor the system, and alert the user when he is about to install a malicious program, or when such a program is running. Whenever Windows Defender detects an installation, or a new program trying to run, it will quickly analyze it. The actions it takes depend on the program's category.

This quick scan is based on the so-called Security Agents, which monitor various part of the system. You can enable or disable them from the Windows Defender configuration screen (reached by opening Windows Defender and clicking Tools on the main toolbar, and then clicking Options on the Tools and Options page). Windows Defender can monitor various parts of the system, like the applications that start automatically, Internet Explorer's downloads or the execution of applications.

Internally, Windows Defender distinguished between three types of programs. Those programs which are known to be legitimate are silently left to run normally, and the user is not even prompted about them. Some other programs are known to be malicious or potentially unwanted. In this case, Windows Defender will alert the user, who can ignore the warning, remove the program or place it under quarantine by clicking Disable. Programs under quarantine cannot be ran, but system administrators may want to store them in order to further analyze them.

A third category about which users must be particularly careful is that of the unknown programs. Although Windows Defender includes a vast list of programs, both malicious and legitimate, some of them are not More often than not, these programs are legitimate, but if you have very sensitive private data on a system, you may want to make sure. Usually, a simple Google search will reveal what you need to know.

Besides protecting your system from malicious software, Windows Defender also includes Software Explorer. Software Explorer shows very detailed information about every piece of software installed on your computer. This can be used not only for managing installed programs, but also to help you determine if a program represents a security threat.

Although it can be disabled or replaced, most users prefer not to do so, because of Windows Defender's tight integration with the operating system and the protection it offers. As long as it is continuously updated (which Windows does automatically), Windows Defender can prove to be a very effective barrier against spyware.