it is fixed length datatype of sql. As we said it ha fixed data space range value from 1 through 8,000. Storage size is n bytes.
As name suggest, it is variable-length datatype. It is also same like CHAR datatype but the main difference is the Storage size of the VARCHAR is the actual length in bytes of the data entered.
Nvarchar can store Unicode characters, it declears variable-length of characters which will only use up spaces for the characters you store. It will not reserve storage like char or nchar.
nChar and nVarchar used more sapce than regular char and varchar so use them only if you really needed by you.
Hope it helps
Editor, DotNetSpider MVM
Microsoft MVP 2014 [ASP.NET/IIS]