orderBy

This is the most complicated modifier, but that isn't saying much. It simply allows you to choose which field you want to order your results by.  The most common use of this is to get items that were published the most recently:

{'type':'page','orderBy':'-publishedAt'}

OrderBy takes a field as a value.  If it has a '-' in front of it, it will order them in reverse.  It will order things either numerically or alphabetically depending on what type the field is.