What requirements must be met for a class to be considered an entity in the context of development?

In the context of development, especially in Domain-Driven Design (DDD), a class is considered an entity if it possesses the following characteristics:

• Unique identity: the object has a unique identifier (for example, an id field) that distinguishes it from other objects, regardless of the values of other fields.
• Persistence of identity over time: even if the properties of the object change, its identity remains the same.
• Behavior and state: an entity contains not only data but also business logic related to that data.

Example in Java:

public class User {
    private final UUID id; // unique identifier
    private String name;

    public User(UUID id, String name) {
        this.id = id;
        this.name = name;
    }

    public UUID getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public void changeName(String newName) {
        this.name = newName;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof User)) return false;
        User user = (User) o;
        return id.equals(user.id);
    }

    @Override
    public int hashCode() {
        return id.hashCode();
    }
}

Here, User is an entity with a unique id that defines its identity.