The stage is an installation of a project into the cloud. Before creating stage, the project is just a set of files. Once you create a stage that builds Lambda functions from your api's, API Gateway for that functions and other supporting resources. With that project gets a live endpoint where you can execute your api's.
The stage is located on a node. While creating stage
new you specify node for the stage. You can
have multiple stages of the project. Each can be located on a different node.
While working in the project, there is a notion of default stage. One stage is always
default, so it is the target of all other project commands. So, for example, when you
deploy/test/watch logs..., you execute those commands on the default stage.
To see all the stages and see which one is default there is
ls command, and to change default
When created each stage gets two endpoints: HTTP and WebSocket. Endpoint is URL where stage API's are exposed.
HTTP endpoint will be something like: https://lh5rfrc3gf.execute-api.eu-central-1.amazonaws.com, and WebSocket: _wss://lh5rfrc3gf.execute-api.eu-central-1.amazonaws.com.