What is serialVersionUID and why use it in Java?

Hello everyone! I'm a beginner Java developer, and recently I encountered something I don't understand — serialVersionUID. I read the documentation, but I still don't fully understand why it's needed and how to use it correctly.\n\nI have a simple class for storing user data:\n\n```java\npublic class User implements Serializable {\n private String name;\n private int age;\n \n public User(String name, int age) {\n this.name = name;\n this.age = age;\n }\n \n // getters and setters\n}\n```\n\nWhen I serialize a User object to a file and then try to deserialize it — everything works. But I noticed that many programmers write something like this in their classes:\n\n```java\nprivate static final long serialVersionUID = 1L;\n```\n\nI tried adding this field — the code works the same way.