The class

The class Exception and its subclasses are a form of Throwable that indicates conditions that a reasonable application might want to catch.

The object

An exception is an event, which occurs during the execution of a program, that disrupts the normal flow of the program’s instructions.

When an error occurs within a method, the method creates an object and hands it off to the runtime system. The object, called an exception object, contains information about the error(eg. type, state etc).

throw this object out!

Creating an exception object and handing it to the runtime system is called throwing an exception.

After a method throws an exception, the runtime system (i.e. JVM) attempts to find something to handle it. This is exception handler.