After watching the session, here’s my too long; did not watch summary of the Build 2015 session Introducing the Windows 10 App Model

What is the Windows App Model? It’s a specification of all processes in the app, how it’s downloaded from Store, deployed, started, communication with the OS, how the app lifetime works, how the app capabilities and access rights are managed, how the app contracts, data roaming, device usage work, and also how the uninstallation process is handled.

Windows 10 app model is same across all supported platforms: IOT->Mobile->PC->Xbox->Hololens.

It also defines new App Model for Classic Windows Apps installed from Store – this is a new thing in Windows 10. It solves problem with registry growth/fragmentation, clean install and uninstall. WinRT virtualizes registry/disk access and enforces App Model Policy – Denied access to Drivers, NT services, Admin elevation, Shell extension. Allowed access to Full API and desktop app lifecycle.

App installation – never regret installing an app. Possible to install apps on removable storage. Opt out for disabling it. Encrypted app data.

Developer unlock for sideloading apps – now in Settings, can be disabled via Domain politics. Limit 20 apps on mobile, unlimited on PC.

Multitasking – It’s about battery and memory. Turn by turn navigation and Always running app now possible.

App resume politics – now always resume. Old resume policy for old WP7-8 apps. When app is resumed devs need to handle navigation to home screen.

App to App API – URL based activation, communication. Foreground to Foreground communication. Foreground to Background Task (App service) communication with sending data and receiving data in response.

Adaptive Tile Templates – same Tile size but different content based on actual tile size.

Action Center – same look and feel shared across all platforms. Alarms and Reminders working again, can be viewed in Action Center. Action Center Change Trigger for updating Live Tiles when notification is removed.

Universal Data Store – global API for Contacts, Calendar, Email, Messaging. Some limited for selected developers right now.

Summary – reliable app installation and uninstallation, more flexible multitasking, unified navigation model, URI based activation/communication, richer tiles and Action Center