Context
UnderstandingMVC provides an abstract overview of the Model-View-Controller pattern.
More specific details (independent of the Rails perspective) can be found here:
See UnderstandingWebApplications for a general overview of webapps before tackling how Rails works.
The Rails Cycle
This diagram displays responses of the rails architecture to each request placed by the client. Request A would invoke controller A, request B would invoke controller B. Each invocation would result in a request-specific response and pathway chosen within the architecture.
So this diagram should be interpreted as depicting a family of responses to a family of requests. The Rails-based application is the sum total of requests, ways of handling the requests to produce responses, and the responses themselves.
