Layout can be controlled programmatically, but the more common approach is using a separate XML file
Layout Example
Intents
From Intents and Intent Filters: "Three of the core components of an application — activities, services, and broadcast receivers — are activated through messages, called intents."
In particular, intents are used to start one activity from another and can also function as hash maps for passing custom parameters between activities
Drawable Resources
These are used for the application icon, if nothing else in your project
