struct tm can be an example.
Actually user defined data type made by user like array,structure,union,pointer. the data type which is define by user or programer according to his need is called user define data type and also called the programer define data type........
Data is information. Data type defines the type of data - integer, character etc
A structure is not a data type. We use structures to define new data types (user-defined data types). If we didn't have the ability to create user-defined types we'd be limited solely to the built-in data types and arrays of those types.
A built in data type is a framework's native data type. By default you'd probably have some built in generic data types, such as integer, string, boolean and so on. In the other hand sometimes you can extend the framework's data types, by programminga user-defined data type. In this data type you have to define it's behaviour and structure, and once defined, you can use it the same way you use the default data types. In PostgreSQL or Oracle, you can define data types. You can read about it on their webs.
Both of them is very important in programming.
A database field format refers to the data type and structure used to define a specific field within a database table. It determines how data is stored, validated, and interpreted within that field, such as text, numbers, dates, or binary data. Common field formats include VARCHAR for variable-length text, INT for integers, and DATE for dates.
struct tag_name { data type v1; data type v2; __________ __________ __________ }s1;
"Abstract Data Type"
Data type can be regarded as data structure because we can define our own data type by using typed function. Data types are the category in which the variable are listed to hold the specific value and data structures are the way in which the values and variables are stored in the memory. The use of a data type called structures allows a collection of values possibly of different types to be treated as a single item. Each data structure is built up from the basic data types of the underlying programming language using the available data structuring facilities, such as arrays & pointers
A predefined structure or, more generally, a predefined type, is a type that is defined internally by the compiler implementation. For instance Microsoft's implementation includes predefined runtime information and GUID structures, amongst other predefined types such as size_t. These types are built in to the compiler itself, so you won't find them in a header file. By contrast, user-defined structures (types) are those you define yourself, or are provided for you by a third party.
The data type, like Number, Date, Time, Text etc.
stack data structure.