Today, most applications are coded in one environment (usually custom-built for that project by a developer), then tested in another, and redeployed to yet another for production.

今天，大多数程序都是在一个环境(通常是由开发者为该项目特别定制的)中编写，然后在另一个环境中测试，最后又部署到另一个环境中投入生产。