How can I create custom error messages and logging in my VBA code using runtime error handling?

Use the `Err.Raise` method to trigger a custom error. Provide a unique error number (e.g., greater than 1000) and a custom description. Inside your error handler, you can then use `Debug.Print` or write to a log file to record details of the error (error number, description, date/time, module, procedure name). Consider including information that will allow the user to re-create the error.