Lightning Components are a new UI framework for developing rich applications that are seamlessly mobile. Lightning Components, as their name suggests, are components, or building blocks for developing applications. Lightning is built on top of the open source Aura JavaScript application development framework. You can read more about the Aura open source project at https://github.com/forcedotcom/aura. Aura is event driven, and as a result, so are lightning components. Whenever you are working with components, you'll often run into tags that start with Aura. For instance, when you create a new component, the system will scaffold out the bare minimum component needed to work, something like this:
<aura:component> <!-- your component details here --> </aura:component>
Aura components are actually bundles of many different files separated nicely by concern. Not all of the files need to be populated; for instance, the renderer file isn't required. In the...