Edge is an all new web browser, exclusive to Windows 10 and will be the eventual replacement of Internet Explorer. You're welcome to set any browser as your default, however. To set a default browser, see - Windows 10: Set default programs
One of the changes for those used to Internet Explorer is the star icon. In Edge the star you see on main menu bar is to add a favorite and not to open Favorites, like it was in Internet Explorer.
Below is an explanation of what the icons do.
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