Beta

In order to get useful and realistic feedback from real users, some software companies deliver pre-release software (a beta or beta trial) to a select number of users to try it out and report bugs, make suggestions, or just give significant customers clear evidence of the state of the product and dispel rumors of vaporware.

What is a beta?
In terms of the software development, beta is usually the stage where all major feature implementation should be finished and the software is in the phase of bug fixing, refinement and stabilization before declaring a Final or Release candidate (sometimes called "Gold" as well). Sometimes major changes occur in this stage, but usually only in response to feedback during a beta trial.

Beta, of course, comes after the Alpha stage where major feature implementation usually occurs, is known to be unstable, and not generally fit for anything more than internal trial of carefully selected users. The stage before Alpha some call "Pre-Alpha", "Proof of Concept", or "Prototype".

These stages are semi-formal within the software industry, so "your results may vary".

World of Warcraft
Starting before March of 2004, Blizzard started signing up Closed Beta Test testers from an unknown pool of people using an undisclosed method of selection. The Closed Beta Trial ran for about 7 months ending in more widely available stress test and then an open beta before final release around the end of November 2004.

The "Closed Beta" was the first phase of Blizzard's stress test. There were three servers and virtually no lag existed. This closed beta is also known as the "First Stress Test". The servers were split up into the following:


 * 1) PvE Server (Original Closed Beta Server)
 * 2) PvP Server (Added near the end of Closed Beta)
 * 3) Beta Server 1

During the closed beta, content was delivered in various "pushes," beginning with the Human push. This was followed by Dwarf, Undead, Night Elf, Horde (orcs, trolls and tauren) and then the open beta. During most pushes, only the newest push's content was available -- human characters were unavailable, for instance, while players were testing the undead character experience.

The Burning Crusade
Starting late September of 2006, Blizzard started signing up Closed Beta Test testers for the first expansion, World of Warcraft: The Burning Crusade, from different playing areas. The plan was to introduce additional players to the beta test in subsequent waves, thus people that didn't make it in the starting lineup still had a chance at a Burning Crusade beta spot prior to launch. 

The Closed Beta started in early October 2006. They were split into two servers:
 * 1) Hellfire (PvE)
 * 2) Blade's Edge (PvP)

Wrath of the Lich King
Opt-ins for the public beta began on July 3rd, 2008; the beta began on July 17th.

Beta keys were given out to BlizzCon 2007 and Blizzard Worldwide Invitational 2008 attendees and Blizzard also gives out Beta keys to various organizations (fansites, etc.) for promotional reasons.

Cataclysm
The Closed Beta started June 30, 2010. It ended on November 22, 2010.