What is "varbinary"

Data type varbinary SQL Server is declared with a length specification in the CREATE TABLE statement:

     CREATE table name (..., colName varbinary (n), ...) where n is the maximum column size in bytes (limited to a maximum of 8000), or the word MAX if more than 8000 bytes may need to be stored. (The absolute maximum size is about 2GB as written, see the SQL Server documentation for the current exact maximum.)

For more information, see this entry in the online documentation of SQL Server.