The document discusses provider-hosted apps for SharePoint that use Azure Access Control Service (ACS). ACS issues access tokens to apps using OAuth 2.0, allowing the apps to access SharePoint data and objects. Visual Studio, WebMatrix, and LightSwitch can be used to build ACS provider-hosted apps for SharePoint, which can store data in SharePoint lists, libraries, remote databases, files, and blob storage. The app provider is responsible for deploying remote components and ensuring tenant isolation.