Explain the exception hierarchy structure in programming languages.

In Java, the exception hierarchy is built on the class java.lang.Throwable, which has two main subclasses:

• Error — errors that are usually not handled by the application (e.g., OutOfMemoryError).
• Exception — exceptions that can and should be handled.

The Exception class is divided into:

• Checked exceptions — require mandatory handling or declaration in the method (IOException, SQLException).
• Unchecked exceptions — descendants of RuntimeException, do not require mandatory handling (NullPointerException, IllegalArgumentException).

Thus, the structure looks like this:

Throwable
├── Error
└── Exception
    ├── RuntimeException (unchecked)
    └── Other exceptions (checked)

This allows the compiler and developer to understand which exceptions need to be explicitly handled and which do not.