All organizations in Apigee, by default, have two environments: test and prod. The naming is arbitrary. These environments are merely designed to provide you with one area to work on and test API changes, and another area where APIs are exposed to apps.
Note: Depending on your role, you may not be able to deploy to all environments. Users can only deploy to test environment. If you're an administrator you can deploy to any environment.
Deployment options
You can deploy multiple revisions of an API. It's common to have a revision in prod while another revision is in test as it's being tested or developed. However, each environment can only have one deployed revision of an API, so you can have revision 1 in test and revision 20 in prod. The Revisions table on each API's summary page gives a clear view of which revision is deployed in which environment.
When you deploy an API to an environment, you're undeploying the existing revision. This can impact apps that currently use the API, so be cautious when deploying.
Deploying an API revision
- In the API revision summary, roll over the Deployment Status column for the revision you want to deploy and click the Deploy icon.

- Confirm the deployment. Deployed revisions are indicated in green.
Note: You can also un-deploy a revision by changing its status.