How Internet Explorer Security Zones work
Shouldn't there be a way to differentiate between places whose content you believe is probably safe and other places where you suspect it might not be? That's what Internet Explorer's Security Zones are for.
Different sources deserve different levels of trust. A well known website you've visited many times without problems deserves more trust than a site you've never seen before and know nothing about.
By assigning sites to different zones, you can manage the amount of risk you face. When visiting new unfamiliar sites, your defenses are high, but if a trustworthy site requires additional features, you can put it in the Trusted Sites zone to enable them.
Here are the 4 Security Zones:
Your local computer and the local area network it's connected to, if any. You and your family or coworkers probably have not created malicious files to damage your own computer system, so this zone has a low level of security. Web pages and files in this zone normally run with few restrictions or warning prompts.
Websites you're confident will not try to damage your computer with malicious files. A site only gets into the Trusted Sites zone if you put it there manually. You can base your decision on your experience or the website's reputation. The "trust" implied here only concerns whether you think a site might try to harm your computer. You might or might not like or trust a company in various different ways, for example, but any site can go in Trusted Sites as long as you're confident that its site isn't designed to be malicious and is competently enough maintained that it's not likely to get hacked and become malicious. The Trusted Sites zone has a medium level of security, higher than your local computer but low enough to allow various types of enhanced content to run or be displayed.