What is the private beta?

Question

There is that badge, called the Beta, and it says actively participated in the private beta. Is the private beta different from the beta?

Answer 1

The private beta was for 7 days. Private betas are limited to those who committed to the Area 51 proposal for the site. Here was the proposal for English:

http://area51.stackexchange.com/proposals/1269/english-language-usage

The public beta is open to anyone on the internet, and it lasts from day 8 - n where n is "met the threshold to become a public site". Public betas can go on indefinitely, as long as the site is producing pages that make the internet better and not worse.

The only way to get the private beta badge is to commit to an Area 51 proposal, help the proposal reach the threshold for beta, and participate during the initial 7 day private beta period.

Answer 2

The phases that a proposal on Area 51 pass through are the following:

• Definition; in this phase, user define which questions are on-topic and off-topic. Once there are 60 followers, and there are 5 on-topic and 5 off-topic questions (which means questions that have a score of 20 for being on-topic or off-topic), the proposal goes to the next phase.
• Commitment; in this phase, users needs to commit to the proposal, which means they will ask a minimum number of questions when the proposal will pass to the next step. The exact number of users required to pass to the next phase depends from their reputation, and from how much they are active in other SE sites.
• Private beta; who committed to the site can start using it by asking questions, or answering to questions.
• Public beta; in this phase, all users can ask questions, including who didn't committed to the proposal.

There is a difference between a site in private beta, and public beta: the reputation required for some privileges is very low, during a private beta; once the site passes to public beta, the required reputation is increased, and it will be increased again when the site goes past the public beta.

To make a comparison, I will report the reputation required on Drupal Answers, which is still in public beta, with the reputation required for the same privileges in English Language and Usage, which is not in beta anymore.

Privilege            Drupal Answers   English Language and Usage
----------------------------------------------------------------
Trusted user                   4000                        20000
Access to moderator tools      2000                        10000
Create tag synonym             1250                         2500
Cast close and reopen votes     500                         3000

The badge you are referring to is gained when you partecipate to the private beta phase, which means you committed to the proposal.