In some cases I might use it as a way to intentionally throw a wrench into a machine sort of speak to stop execution of a program at a certain point as a means of debugging, but as of late I prefer to use alternatives to that to catch a state of affairs as to what is happening at a certain point in time. So for the most part the throw statement is just used in the process of making custom errors.
To use a throw statement is a basic way just type the throw keyword followed by a value that reflects what the error is about. For example I could have an add numbers method that will throw and error if I pass it a value other than a Number.
The value can be a string, number, boolean, or an object that should be given certain standard key value pairs more on that later. For now you should get the basic idea at least, the throw statement will cause an error to happen, and then an additional value can be passed as a way to shed some light on what that error is.
So a string can be used to describe the user defined Error, but it might be best to use an Object or The Error constructor to create an object with message and name properties that help to better identify what is wrong when the Error is thrown. This standatd object of sorts can be called you guessed it an error object that contains properties like message that is used to set the string message of the error, but also properties like name, line number, and so forth
When an Error is thrown any catch statement present will of course be executed which can be used to handle the Error