What does the Serializable class do in Java and why is it rarely used in practice?

In Java, the Serializable interface is used to indicate that objects of a class can be serialized — that is, converted into a byte stream for storage or transmission.

Why it is rarely used in practice:

• Default serialization can be unsafe and inefficient.
• Maintaining class version compatibility (serialVersionUID) is required; otherwise, deserialization may fail after class changes.
• More modern and flexible serialization methods are often used, such as JSON, XML, or buffer protocols (protobuf).
• Java object serialization can lead to performance and security issues.

Example:

public class User implements Serializable {
    private static final long serialVersionUID = 1L;
    private String name;
    private int age;
    // getters and setters
}

Thus, Serializable is a simple serialization method, but in real projects, other approaches are often preferred due to limitations and risks.