If you open your options by pressing "escape" there will be several tabs at the top of the page. The "realms" tab will be the one that looks like two ball bearings in front of a gear. There are several realms, all displaying from A to Z. Each realm is like a complete copy of the spiral and different players are there, almost like a Parallel universe, if you out it one way XD. You don't really have to worry about realms, unless you prefer to be alone in a world, or have lots of people with you.
The realms are just there to keep places from overcrowding, since there are so many people on at the same time :P otherwise, just imagine the commons! XD
