Opera browser offers the choice to identify itself as Opera, Internet Explorer, or Firefox. Every time your browser requests a page from a Web site, it includes several pieces of information, among them the browser type. That gives the site a chance to return a page specifically tuned for the browser in question, or at least to omit features not supported by the calling browser. However, Web designers don't always handle this information correctly. For example, they may assume that every non-IE browser is Netscape or suppress more features than necessary for non-IE browsers. In most cases you'll want to have Opera identify itself as IE (the default). This does not in any way open up your system to IE-specific vulnerabilities. All it does is lie to each and every Web site you visit, forcing them to give you the IE version of the requested Web page.