Nokia Belle is the operating system inherited from Symbian platform. In 2012, the Symbian S60 has big changes and from here on it has been called Nokia Belle (or Symbian Belle).
Symbian Belle comes with a number of improvements like an improved user interface with widget redesigns, movable & resizable widgets, six customisable homescreens, improved social media support, better multitasking experience, improved status bar, deeply integrated NFC support, and new Microsoft Apps.