Specifies whether you want Internet Explorer to remain your default Internet browser, even if you install additional Internet ...

Specifies whether you want Internet Explorer to remain your default Internet browser, even if you install additional Internet browsing software.  When this check box is selected, each time Internet Explorer starts it checks to make sure it is still registered as the default Internet browser. If another program is registered as the default browser, Internet Explorer asks whether you want to restore Internet Explorer as your default browser.