Create and throw your own custom errors.
While `try...catch` is for handling errors, the `throw` statement is for creating them. It allows you to generate user-defined exceptions. You can throw any expression, such as a string or a number, but it's best practice to throw `Error` objects (or objects that inherit from `Error`). This is because `Error` objects contain valuable debugging information, including a `message` and a `stack` trace, which helps pinpoint where the error originated. Throwing your own errors is a powerful way to enforce rules and handle exceptional conditions within your own functions. For example, if a function receives invalid arguments, instead of failing silently or returning an ambiguous value, it can `throw` an error to immediately signal that something is wrong. This makes your APIs more robust and easier to debug for other developers (or your future self). The thrown error will propagate up the call stack until it is caught by a `try...catch` block. If it's never caught, it will terminate the program. This mechanism is essential for building predictable and maintainable code by making exceptional circumstances explicit.