What is a development environment and how do I set it up?

I'm looking at nodepad: http://dailyjs.com/2010/11/15/node-tutorial-3开发者_JAVA技巧/

And they have different development environments, development, staging, production.

How do I configure my server appropriately so that the app would know what environment it's supposed to be?

Thanks.

See the express framework documentation:

To alter the environment we can set the NODE_ENV environment variable, for example:
$ NODE_ENV=production node app.js