With the 1.1 release of Django came several major new features, prominent among these is aggregation, which was among the most oft-requested for Django's ORM. The addition and manner of implementation of this feature highlights several fundamental philosophies within Django, as well as provides new possibilities. Fundamentally aggregates support in Django means a way to answer queries such as "show me all the authors who have published more than 1 book" or "show me the most expensive book".
When you’re developing a personal website, a blog, or a website for a small client, you typically don’t spend a whole lot of time worrying about setting up dedicated development, staging, and production environments. When that small client becomes bigger, your personal website becomes a brand, or you accidentally release broken code, that’s when it makes sense to start separating out those environments.