Apps are modular apps that live on top of your Airtable bases. From map, chart, and timeline, which introduce new ways to visualize your work, to Google Cloud Vision, translate, and send SMS, which help put it into action, apps not only enhance your existing Airtable use cases, but also introduce completely new ways of building your own app workflows.
You can add an app to any of your bases on any Airtable plan. It's worth noting that there are various app limits depending upon which plan your workspace is on. More on plan differences here.