Editions allow you to give preference to the content you're interested in. If you are a new visitor, or haven't selected a particular edition, you will be taken randomly to one of five editions until such a time that you select 'Make edition default' at the top of the page.
The five editions are:
By making an edition default, you can still get to all content on Coaster Kingdom, but you will find content such as the 'Ride Reviews' panel being orientated towards your chosen ride type. If you have selected Coaster Edition, for example, expect to find recent roller coaster reviews shown.
There is also a feed available on each page for that chosen ride type, so that you can be told every time a coaster, dark ride, spin ride or water ride review is added to the site.