In Autonomous, tests are organized around a few core concepts. Each one represents a distinct part of how tests are created and managed. This section will guide you through each of these key ideas.

- **[Applications](/content/docs/autonomous/core-concepts/applications/index.html)**
  
  An application represents an AUT (application under test). This groups all tests that belong to the same website, application, or department that should be managed together.

- **[Tests](/content/docs/autonomous/core-concepts/tests/index.html)**
  
  A test takes screenshots of all or selected pages in your website in different browsers and devices, and uses those images as a baseline.

- **[Plans](/content/docs/autonomous/core-concepts/plans/index.html)**
  
  A plan allows you to run one or more tests together using the same environments and schedule.

- **[Browsers & devices](/content/docs/autonomous/core-concepts/browsers-and-devices/index.html)**
  
  Browsers and devices represent virtual browser settings or mobile devices that the test should run on.