binary and varbinary
Binary data types of either fixed-length (binary) or variable-length (varbinary).
binary [ ( n ) ]
Fixed-length binary data of n bytes. n must be a value from 1 through 8,000. Storage size is n+4 bytes.
varbinary [ ( n ) ]
Variable-length binary data of n bytes. n must be a value from 1 through 8,000. Storage size is the actual length of the data entered + 4 bytes, not n bytes. The data entered can be 0 bytes in length. The SQL-92 synonym for varbinary is binary varying.
When n is not specified in a data definition, or variable declaration statement, the default length is 1. When n is not specified with the CAST function, the default length is 30.
Use binary when column data entries are consistent in size.
Use varbinary when column data entries are inconsistent in size.