Microsoft's Internet Explorer gives you several ways to protect your computer from malicious websites and virus-infected code. For most of us, Internet Explorer's default settings are secure enough. However, if you decide to tweak the security settings at 2 a.m. after watching Sandra Bullock run like a girl in "The Net" for the 17th time, you should have some understanding of the consequences.

Here's a quick rundown of the security settings you can adjust to suit your browsing style and level of paranoia.

Warning: You can seriously mess up your browser and leave your machine vulnerable to nasty code if you tinker with the custom security settings. This activity is best left to professionals like IT managers and security consultants.

Find the security settings

From the Tools menu, select Internet Options. Click the Security tab. You'll see the "zones" across the top, with Internet highlighted and the security level most likely set at medium (the default).

Get in the zone

Before you set any security levels, you need to divide your world into zones. Internet Explorer categorizes websites based on how much you trust them. All sites assigned to a particular zone share permissions and restrictions you specify for the entire zone.

• Internet: Catch-all category containing every site not assigned to any other zone.
  
• Local intranet: Contains addresses you can reach without going outside your LAN or company firewall, such as your internal human resources webpage.
  
• Trusted sites: Holds both external and internal sites, but you have to add them individually. Typically, these are the sites you trust enough to lower your drawbridge.
  
• Restricted sites: Holds both external and internal sites, but you have to add them individually. Typically, these are the sites for which you prepare the Internet equivalent of a hydra-infested moat and cauldrons of boiling oil, just in case.

Internet Explorer assumes that files already stored locally on your hard drive are safe, so you can't assign them to a zone. To learn how to assign sites to zones, click here.


To add a URL to the list of sites within the Trusted or Restricted zones, click the button for the zone and then the Sites button. Add the URL in the appropriate field and click Add. When you're done, click OK to return to the main security settings screen.

For the Intranet zone, click Sites, then select the appropriate check boxes for the categories of sites that belong here. To add individual URLs, click Advanced.

Prepare your defenses

Select the zone to which you want to assign a security level. Then drag the slider bar up to increase or down to decrease security. As you move the slider, text appears that details what each level allows and disallows for that zone.

For example, if you set the Internet zone to medium-low security, you get the same level of protection as the medium setting, except that you don't receive a warning dialog box every time you enter or leave a secure page or download a file. Setting the level to high actually disables certain features and prevents you from experiencing the full effect of some websites -- a plus when dealing with the nefarious, but too restrictive when visiting places you trust.