On the new platform (aka Platform X), everything is Source/Event/Destination.
Sources (your website, app or server) collect your user actions by sending events.
These events are sent to the platform servers and are then enriched, normalized and translated in each tool (Destination) format, so that they can be sent to your chosen destinations.
You can learn more in the Concepts section.
From a mobile application, you can either use one of our SDK (Android, IOS, ...) or use our HTTP tracking API if you don't want to use a SDK.
3. Format events
Events are the new format of your data. As explain in the event documentation, common events have to be sent in the standard format (name and properties) to benefit from plug&play features.
For specific events, custom events name is possible. Nevertheless, please use standard properties in custom events, as far as possible, to benefit from automatic mapping, automatic QA, and plug&play features.