Merge branch 'usage' into 'master'

CDI vs CAI INPLATFORM-146

See merge request !12

docs/concepts.md

 # IICS Concepts
 
-### Secure Agent
+## Secure Agent
 A Java program that runs all tasks and enables secure communication across the firewall between our organization and 
-IICS. More details can be found [here](https://docs.informatica.com/integration-cloud/cloud-platform/current-version/administrator/runtime-environments/secure-agents.html).
\ No newline at end of file
+IICS. More details can be found [here](https://docs.informatica.com/integration-cloud/cloud-platform/current-version/administrator/runtime-environments/secure-agents.html).
+
+
+## Cloud Data Integration (CDI) and Cloud Application Integration (CAI)
+
+![CDI-CAI](./images/CDI-CAI-venn-diagram.svg)
+
+The diagram source can be found [here](https://app.lucidchart.com/documents/edit/5ab81deb-0dd1-4ca4-9f8b-f1fa2706ec79/0_0).
+
+CDI and CAI are IICS services that are used for integration projects. Depending on the integration criteria, projects can be built using either CDI or CAI, or a hybrid approach when it would be beneficial to an individual project. 
+
+### Cloud Data Integration
+
+Cloud Data Integration (CDI) is IICS's data integration service that allows you to create, schedule, and monitor tasks. It provides a variety of connectors to various data sources and provides mechanisms to transform and map data from source to target.
+
+CDI is best used for projects that have the following characteristics:
+
+- Large batch jobs, i.e. nightly uploads
+- Flat data structure
+- High latency environment
+- Periodic or scheduled jobs
+- Connectors exists for environment
+- Data migration
+- Data Integration Hub
+
+### Cloud Application Integration
+
+Cloud Application Integration (CAI) is IICS's event-driven and service-oriented application integration service. It provides capabilities such as event processing, service orchestration, and process management.
+
+CAI is best used for projects that have the following characteristics:
+
+- Small batch jobs, i.e. single record updates
+- Nested data structures, i.e. JSON, XML
+- Low latency environment
+- Event based / Real time integrations
+- Direct access to APIs
+- Business Processes
+- Composite Services, APIs