1. Characteristics of data: it can be input to a computer and can be processed by a computer program
2. Data is an abstract concept, which can be classified into types in programming languages. Such as: int float char, etc.
3. Data element - the basic unit of data, data item: a data element consists of several data items
4. Data Object - a collection of data elements of the same nature
5. The data elements are not independent, there are specific relationships, these relationships are the structure
6. Data structure refers to the relationship between data elements in a data object. Before writing a "good" program, it is necessary to analyze the characteristics of each object in the problem to be processed, as well as the relationship between the objects
7. Logical structure
Set structure - there is no special relationship between data elements, only the same set
Linear structure - one-to-one relationship between data elements
Tree structure - there is a one-to-many hierarchical relationship between data elements
Graph structure - there is a many-to-many relationship between data elements
8. Physical structure - the storage form of logical structure in the computer
Sequential storage structure - store data in consecutive memory locations
Chained storage structure - store data in any storage unit, and find the relevant data element by saving the address