Firefox to US$7,500 cash reward) to researchers who discover severe security holes in Firefox. Official guidelines for handling security vulnerabilities discourage early disclosure of vulnerabilities so as not to give potential attackers an advantage in creating exploits. Because Firefox generally has fewer publicly known security vulnerabilities than Internet Explorer (see "Comparison of web browsers"), improved security is often cited as a reason to switch from Internet Explorer to Firefox. "The Washington Post" reported that exploit code for known critical security vulnerabilities in Internet Explorer was available for 284 days in 2006. In comparison, exploit code for known, critical security vulnerabilities in
Internet Explorer Mobile other Microsoft devices besides the smartphone in use: if a user is logged in with his Microsoft account on both his Windows 8.1 device and Windows Phone device, tabs on Internet Explorer 11 will synchronize automatically. Microsoft made several changes to Internet Explorer Mobile to make the browser more compatible with sites designed for mobile Safari (iOS) and Chrome (Android). To accomplish this, Microsoft adopted features used in Safari and Chrome, emulates legacy WebKit features, and claims to web servers that it is iOS or Android compatible. The new version of Internet Explorer Mobile was released with Windows Phone 8.1