As described in [this news item](https://www.metaculus.com/news/2019/08/04/introducing-the-domain-system/), a new Metaculus "domain" system has recently quietly gone live.  

In short, the idea is that it is now very easy to create domains, which create sub-divisions of the full metaculus community (which we've started referring to as "Metaculus prime", or "MP"). The idea of a domain is:

* Each question has a set of domains associated with it, and it appears on those domains.

* Each user has a set of domains to which they have access, but all users have access to MP.

* Each domain has a top-level URL of form [domain].metaculus.com

* Each domain has its own leaderboard, and can have some other customizations, such as a few different look-and-feel options, different categories, etc.

* Users carry some of their information (levels, powers etc.) across domains but not all of it (with details TBD.)

The hope here is that domains can be used in a few different ways, e.g.,

* By a group or organization that wishes to create a set of questions private to that group, but optionally cross-post some of them to MP.

* By Metaculus or another group wishing to create a domain focusing in much greater detail on some particular issue, where some of the "top line" questions would be cross-posted to MP, but some finer-grained or more technical questions would be domain-specific.

We're currently in the process of integrating what was previously a private instance, ai.metaculus.com, into the domain system. So you'll probably start to see some cross-posted questions soon.

This discussion question is to invite feedback.  For example:

* Questions about how domains work?

* What uses do you see for domains?

* How should some of the details work?  For example:

    * Should you carry your level and score across all domains, or should it be individual to the domain, or both?  

    * What happens when a question is cross-posted when it's already opened?