Blob, which is short for Binary Large Object, is a collection of data in binary form, which is stored as a single unit in a database management system. They can be over two billion characters long, and require more space than other data types. Generally, the storage system you have will determine the size of the blob.
What the blob is used for?
Unlike most data types such as characters, strings, integers or floating point numbers which store numbers and letters, the variables of blob full form have variable length. They are used in storing data in the form of audio, multimedia objects, video clips or images. For instance, an album for photos can be stored using a blob data in the database, and the captions created by a string data type.
A blob full form usually requires more space as compared to other data types because they are used for storing heavier data. How much data a blob can store depends on the type of database, even though some big databases permit storage of many gigabytes of data.