orderBy() and orderByDesc() both sort the results of your query before they're returned, so that when you iterate through the results using the next() method, you get the results in the appropriate order.

The orderBy() and orderByDesc() methods both accept one argument: The name of a field in the database table specified when instantiating the GlideRecord object you're calling this method on. This is the field that will either be sorted low-to-high/a-to-z/past-to-present if you used the orderBy() method, or the opposite if you called orderByDesc().