They are broadly divided into two categories: Primitive Data Types: Store simple values directly in memory. Non-Primitive (Reference) Data Types: Store memory references to objects. Primitive types are the fundamental data types that store single values.

Data types in Java define the kind of data a variable can hold and the memory required to store it. They are broadly divided into two categories: Primitive Data Types: Store simple values directly in memory. Non-Primitive (Reference) Data Types: Store memory references to objects.

Apart from primitive data types, Java also has reference data types referred to as non-primitive ones. They contain a memory address of variable values that are not stored directly but instead store the value at that address. All variables outside of the eight primitive data types are non-primitive (or reference) types.

Reference data types are not predefined by the language but are created by the programmer. They include classes, interfaces, arrays, and enumerations. Variables of reference data types store references (memory addresses) to objects rather than the actual data. For example: // Creating an object of the String class String str = "Hello, Java!";