What font does Windows use in dialog boxes? [duplicate]

What font is used for the interface in Windows Phone 8 and Windows 8? Is this font free to use?

Solution 1:

Windows 8 Developer Preview uses Segoe WP in some places (mostly Metro styled apps and settings) and the Windows 7 default font Segoe UI on the desktop.

The Consumer Preview of Windows 8 will use Segoe WP everywhere.

The fonts are free to use. You get them if you install Visual Studio 2010 or other free developer tools from Microsoft for creating Windows Phone apps.

Solution 2:

By default, Segoe UI is the font used by Windows.

Windows XP used Tahoma for most user interfaces.

Windows 98 used MS Sans Serif.