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.
Check out this four minute video to learn more about how App Service relates to earlier Azure offerings and what's new in it.
Learn more about how to get started with App Services here.