In hosted software development, the environment refers to a server tier designated to a specific stage in a release process. The purpose of these environments is to improve the development, testing and release processes in client-server applications. The most common environments are described below.
This is where the software is developed – it’s the working environment for individual developers or small teams. The purpose of this environment is for the developer to work on local host, separate from the rest of the team, allowing them to make various changes without worrying that it may alter the work of the other members of the team.
It is used to assemble, test and review the application before it goes into production. Usually the staging environment tries to simulate as much as possible the production environment (hardware and software-wise). Normally, before releasing an update version of the application on the production environment, the update must be tested on the staging environment. This environment can also be used as a demonstration/training environment.
It is the “live” environment, where the final application goes out to the world and becomes active.
To switch from one environment to another use the Subversion source code.
Using SVN on Aptana is an article that explains how to set your development environment on your local computer and then to change it on your staging environment.
To better understand the development of an application using environments, check this helpful article http://dltj.org/article/software-development-practice/