What is GETDATE() ,SYSDATETIME(), GETUTCDATE(), SYSUTCDATETIME() ?

GETDATE() : Its precision is in milliseconds.
SYSDATETIME() : Its precision is in nanseconds.
GETUTCDATETIME() : Returns data as UTC time ( Coordinated Universal Time ) and its precision is in milliseconds.
SYSUTCDATETIME() : Returns data as UTC time ( Coordinated Universal Time ) and its precision is in nanoseconds..