We're going to introduce an example that we're going to use throughout some of these discussion to help illustrate some important principles. And the example is an application that we're going to call iRemember. And this is an application that is about helping people to remember memories and attach them to specific places. So, you can imagine that you're a graduate of a college or you're a graduate of a school, or there's a particular place, physical location that has meaning to you, and different locations. I'm going to use the example of Vanderbilt because I've been there for a long time, so you can imagine, I've been at Vanderbilt and the building where I teach classes has memories to me. The campus where I walk around, this beautiful campus with all these trees, I have memories of walking around on wonderful sunny days and seeing the campus and all of these trees that are there. I have memories of the friends that I've known there. All of these things that I'd like to be able to keep track of them. So, the idea behind the iRemember application is that it serves as a central hub for all of these memories that we have about a physical location. So, we can go and attach memories to specific places on a map. So, as we do this we may go and attach things to part of Vanderbilt, some building on Vanderbilt that I remember or some walkway to another building where I had just wonderful walks in between classes. And so, the idea behind the iRemember app is that we can go and enter in these memories and attach them to specific geocoordinates within the app, and then be able to pull them up, and view them, and search them in different ways, or publish them and allow other people to go and discover these memories that we've saved through our app. So, maybe if somebody else can come along. And they can see my memory that I've published about this part of Vanderbilt's campus. And they can also reminisce about it and add their own sets of memories. And so be able to create this idea of rich experience around physical locations and discovering these locations. This is an app that was originally thought up by Adam Porter at the University of Maryland, who did a wonderful MOOC on beginning Android and we've worked together. And so, I want to use this app as our example that we walk through. Now we can do a number of things with this app, for example, not only maybe want to allow users to directly input memories, but we may want to allow other apps to provide, we may want to give them some type of API that allows them to share memories from their app that are maybe different than what we thought about. So, maybe within the Camera app, we want to be able to share a memory into the iRemember app. Or maybe we receive a wonderful phone call about something incredible that happens and we want to somehow document it and share it into the iRemember app. Or maybe it's a post that we just made on Twitter, or Facebook, or something else and we want to share that into the iRemember app. So, we may not only be able to create this app where users are inputting data, we may be also provideding an API for other apps to provide data to the iRemember app. We may have other apps going and discovering it. And it's creating this rich environment whereby we can go and attach memories to physical spaces and then discover them later on.