The Basics
Projects
At the top level of your application you have a project definition. This definition is used on the server only and is never sent to the client.
Overview
Project definitions are effectively the root node of all projects and contain information about the project itself such as the project id, name and root user reference, as well as being reversed referenced by all other entities i.e. every other table record will reference it's root project id.
You should know!
You cannot create multiple projects within a single account, it's only possible to have one project per user account.
You should also know!
Project data is not and cannot be sent to the client.
You can review the full Project API specification here.