A user defined type ( sometimes called a record or struct ) are clumps of the other major data types stored in the same location in memory.
Procedural Programming Edit
In procedural languages, types are generally just clumps of the other types. Some fields can be binary depending on language probably.
Object Oriented programming Edit
In Object-Oriented programming these are more advanced in that they have associated routines with them that are used to change data so it behaves like the the original programmer intended.
|Programming||Character - Floating point Number - User-defined Type - Integer|
|Database||Character - Decimal - Integer - Blob|