Basic Concepts of Data Structures

1. Data

The structural collection of facts, figures, concepts, or characters managed and processed by a computer system.

2. Data Element

The fundamental unit of data. A data element can consist of several data items. A data item is the smallest, indivisible unit of data.

3. Data Type

A collection of values and a set of operations defined on those values.

4. Abstract Data Type (ADT)

A mathematical model implemented in a computer system, which specifies a collection of data objects, the relationships among them, and a set of basic operations (e.g., modeling a Finite State Machine).

5. Data Structure

The specific structural relationship existing among different data elements. A data structure encompasses three core aspects: Logical Structure, Storage Structure, and Data Operations ($\text{Program} = \text{Algorithm} + \text{Data Structure}$).

6. Logical Structure

The conceptual relationships between data items, independent of how they are physically stored in memory. It is broadly categorized into linear and non-linear configurations.

```mermaid graph TD Logical_Structure[Logical Structure] –> Linear_Structure[Linear Structure] Logical_Structure –> NonLinear_Structure[Non-Linear Structure] Linear_Structure –> General_Linear_List[General Linear List] Linear_Structure –> Restricted_Linear_List[Restricted Linear List] Linear_Structure –> Generalized_Linear_Extension[Linear Extension] Restricted_Linear_List –> Stacks_and_Queues[Stacks and Queues] Restricted_Linear_List –> Strings[Strings] Generalized_Linear_Extension –> Arrays[Arrays] Generalized_Linear_Extension –> Generalized_Lists[Generalized Lists] NonLinear_Structure –> NonLinear_Tables[Non-Linear Tables] NonLinear_Tables –> Sets[Sets] NonLinear_Tables –> Tree_Structures[Tree Structures] NonLinear_Tables –> Graph_Structures[Graph Structures] Tree_Structures –> General_Trees[General Trees] Tree_Structures –> Binary_Trees[Binary Trees] Graph_Structures –> Directed_Graphs[Directed Graphs] Graph_Structures –> Undirected_Graphs[Undirected Graphs]