What is the difference between + and ++ when concatenating nvarchar?

Question

I just saw sql code which concats 2 strings with '++'. I always use single plus like '+'

what is the point of using '++'

 PRINT 'TEST ' ++ 'TEST'

Answer 1

PRINT 'TEST ' ++++++++++++ 'TEST'  

or

PRINT 5+++++++++++++++++++++2

Still works because, "Although a unary plus can appear before any numeric expression, it performs no operation on the value returned from the expression. "

Look into below documentation: https://msdn.microsoft.com/en-us/library/ms174362.aspx