Any Unicode data can be stored in a nvarchar column. An 8-bit codepage may only be used for varchar columns. Varchar is recommended, according to some, because it uses less space. This, in my opinion, is not the right response. Codepage incompatibilities are annoying, and Unicode is the solution. Nowadays, there is really no need to waste time fiddling with code pages because disc and memory are so affordable.
Internally, Unicode is used by all current operating systems and development environments. You can avoid doing encoding conversions each time you read from or write to the database by using nvarchar instead of varchar. Conversions are labor-intensive and prone to mistakes. Additionally, recovering from conversion errors is a challenging issue.
I still advise utilizing Unicode in the database even if you are interacting with an ASCII-only application. With Unicode, database collation techniques will perform better. When interacting with other systems, Unicode prevents conversion issues. You will also be getting ready for the future. For any legacy system, you need to support, you can always verify that your data is limited to 7-bit ASCII while still taking advantage of some of the advantages of full Unicode storage.