App Service is a platform-as-a-service (PaaS) offering of Microsoft Azure. Create web and mobile apps for any platform or device. Integrate your apps with SaaS solutions, connect with on-premises applications, and automate your business processes. Azure runs your apps on fully managed virtual machines (VMs), with your choice of shared VM resources or dedicated VMs.
App Service includes the web and mobile capabilities that we previously delivered separately as Azure Websites and Azure Mobile Services. It also includes new capabilities for automating business processes and hosting cloud APIs. As a single integrated service, App Service lets you compose various components — websites, mobile app back ends, RESTful APIs, and business processes — into a single solution.