Test realm
From WoWWiki
A test realm or test server is a realm made for trying out features in development for the next patch. Blizzard occasionally announces Public Test Realms or PTRs for players of World of Warcraft to test features. Blizzard has also recently done a Tournament Test Realm or a TTR to get ready for the Arena Competition.
You can make a character on the test realm from a copy of one of your characters on a normal realm, or from a premade. Whether there will be premades or not, will be clearly announced. Players on test realms should not be surprised by character wipes, item wipes, or frequent downtime to make changes or apply patches, so don't get too attached to your character on these servers.
For a guide to getting on the test realm, see Getting on the Test Realm.
