Salesforce1 is built on Aura. The Salesforce team has actually developed Aura specifically for making the mobile experience better. Since then, the Aura framework has grown immensely. Now, most of the lighting framework is using Aura.
Lightning Components are essentially a rebranding of "Aura on the Platform"
Why use Aura?
Aura comes with a rich and extensible component set to kick start building apps. You don’t have to spend your time optimizing your apps for different devices as the components take care of that for you.
Some key features of aura include:
- Tag-based layout & component definition
- Encapsulated UI development with a strongly typed event model
- Object-oriented programming behaviours
- Encapsulated bundles with models, controllers, CSS, static resources and markup
- Integrated functionality with performance testing capability
- Responsive and Mobile first approach
There are two parts of aura, an open-source package and Force.com package. The open-source package is available now on GitHub and you can start playing with an early version of it. Right now the core framework is server side Java but there are adapters for essentially any JVM-based language (Heroku FTW!). Languages such as Node.js and .NET will be a little tougher to implement but Doug seems very open to talking about a road map. There is also an Eclipse plugin but I haven’t found reference to it yet.
So how can you get started? You can certainly take a look at the aura project on GitHub. but I will highly recommend forking the aura-note sample application as it is loaded with some great code to get you started. Also, go ahead and submit issues and ideas as Salesforce.com is very receptive.
Adding Lightning components on it will let developers start exploring this framework.