Microsoft's Project Madeira shows how the lines continue to blur between what an app is and what a service is. In this case, the Project Madeira basic business apps for Windows, iOS, and Android exist within Outlook, so users can access them without ever leaving Microsoft’s email program.

If that seems confusing, consider how the Outlook apps for iOS and Android include a calendar, but without breaking the calendar portion out as a separate application. That’s how Madeira works.

Technically, Microsoft defines Project Madeira as a public cloud service (or software as a service) for Windows, iOS or Android devices, running on top of Microsoft Azure. It just happens to run within Outlook. The Madeira services are designed for small businesses with 10 to 100 employees—small enough, according to Microsoft, that they have neither the incentive nor the funds to invest in an enterprise resource planning system.

Microsoft promises that Madeira will include financials, dimensions, sales and purchase management, inventory, CRM (opportunity management), multi-currency, and business insight. Eventually, Microsoft promises third-party developers will create extensions for Madeira, which will be sold in an apps marketplace.

For now, Project Madeira exists as a “public preview,” Microsoft said. The service is scheduled to become generally available in the U.S. during the second half of 2016, with other countries to follow.

Why this matters: Think of this as something like an apps-centric version of Inception: platforms upon apps upon platforms. Microsoft’s Office apps began life as apps running on top of Windows. But Office is now also a platform, with business-intelligence tools like Microsoft PowerBI running on top of Microsoft Excel, and Microsoft’s Delve and Outlook Groups tapping into the knowledge stored within Outlook. Madeira is just another set of tools running on top of Outlook, but purpose-built for the task at hand.