A PTR is a special testing environment where developers allow the public to test early releases of video game updates. Short for Public Test Realm, or Player Test Region the special server often has limited access, and is generally not open to everyone. The realm allows developers to soft-launch patches, and other software that is in late beta, for user testing, and feedback.
Progress, unlocks, and monies (XP) earned in the PTR rarely carry over to the live environment. However sometimes publishers will up-date PTR accounts to match live accounts to facilitate testing. Most players PTR accounts will lag behind their live account’s progress.
The PTR often is accompanied with a feedback forum to allow gamers to report bugs, and make comments about a patch. Usually restricted, the forum is only open to PTR players and representatives from the publisher. Comments and feedback may cite specific bugs, voice concerns, or offer suggestions. Game balance is often a hot topic discussed in PTR forums.
Blizzard describes their Public Test Realm/Region (PTR) as a “special service you can use to test patches before we release them to the public. When we start a PTR test, we’ll announce it on the game’s website. We run PTRs in English, French, German, and Korean.”
Here is a typical Steam Community PTR description: