Binary Large Object Data is represented by the following:

> Unlike a CLOB, which stores a long character string, a BLOB stores a long bit string. These two data types are not interchangable.

> BLOBs are used to store large multimedia data such as digitized pictures, medical photos, 3D graphics, videos, audios, audio/visual movies, data recordings, etc.

> BLOBs can be either fixed in length or variable in length.

 
> A BLOB can not be used as a PRIMARY KEY, FOREIGN KEY, or UNIQUE predicate.
    A BLOB can not be used in any comparison other than equal or not equal.
    You also can not use BLOBs with DISTINCT, GROUP BY, or ORDER BY.

> RDBMS systems don’t try to interpret BLOBs, that is left to you and your application.

> SQL:1999 introduced BLOBs as a data type.