> ## Documentation Index > Fetch the complete documentation index at: https://docs.revyl.com/llms.txt > Use this file to discover all available pages before exploring further. # Core Concepts > The mental model for Revyl in 60 seconds How the core primitives connect ## App Your mobile application in Revyl. An App is a container for builds: iOS Production, Android Staging, whatever variants you ship. Create one App per platform per environment. See [Apps](/builds/index). ## Build A specific uploaded binary inside an App (`.apk` for Android, `.app` bundle for iOS). An App can hold many Builds over time. One is always the **active build** that tests run against by default. ## Test A sequence of steps that runs against a build on a device. Steps are written in natural language ("Tap Sign In", "Verify the home screen loads") and the AI agent executes them. See [Tests](/tests/index). ## Session A live device instance. When you run a test or start one manually, Revyl boots a real iOS or Android simulator you can interact with. Sessions can also be [compiled into tests](/tests/creating-tests/recording). See [Develop](/develop/index). ## Report The output of every test run. Includes pass/fail status, video replay, AI summary, device logs, and network activity. Reports are shareable via public links. See [Reports](/tests/reports). ## Workflow A named group of tests that run together in parallel. Trigger a workflow from the UI, CLI, API, or CI/CD to run your whole suite at once. See [Workflows](/tests/workflows).