Aura is a UI framework developed by Salesforce for building dynamic web apps for mobile and desktop. It uses a component-based and event-driven architecture to support multi-tier development and a scalable lifecycle. Aura powers the Salesforce1 mobile app and other Salesforce products. It provides base components, controllers, and server-side logic to build apps using HTML, JavaScript, and Apex code. Lightning Components are built on the open source Aura framework.