Gestures are interesting. When we make a gesture, We do it often times in mid-air. We're not touching anything. Or sometimes with these devices we, well I want to change the page, I do that. But, what do the gestures mean? How do we learn them? How do where to do them and which ones we should do? So, remember when I came into this room? I took out this card, and I swiped it. Well, I had to know where to swipe, and I had to know, how do I swipe it? This way, or this way, or this way, or this way? Four different possibilities, only one of which would work. And, it's not always obvious. How do I know it did work? Well, there was a green light that came on, that green light is feedback. The first problem, knowing what act to do, is discoverability. The second one, knowing that it worked, or didn't work, is feedback. Now when I entered the room, I looked around and there was Scott, and I made a gesture saying oh, hello, what do I do now? And he pointed. Pointing's a gesture. So it told me to come here. So that's a fairly universally understood gestures. Not all gestures are universal. I came here and sat down. Then you saw me do a different kind of gesture. You may not have thought it was a gesture, but it was pushing a button, but that's a kind of gesture. And the hard part is discoverability, where do you push the button? This one is here, and this one is Here, and they're all in different places. Well, that's the discoverability problem, and it's aided by the fact there's some physical button, that once I see it, I know where to push. But after I do that, then what? So here, Well, I see a screen, oh, it says slide to unlock. So I could slide to unlock it. And then it says enter a passcode. Or I don't really have to do that, I could, instead, put my finger here. Now is that a gesture? It's kind of a gesture, even though I'm not moving. And that works. It recognizes my fingerprint. When I'm here, now what? Well, I can swipe the screen left or right. Or I can swipe this way, and oh, look at that, there's my calendar. Or I could swipe from half-way down, and oh, it's search. Now, there's no hint. There's no indicator that says coming from the top is the calendar. And coming from half-way down is search. And coming from the bottom up is, oh, looks like sound control. And going from the right, oh it moves the screen, and going to the left, oh, it moves the screen. Basically, no discoverability, but there is good feedback. Or this one. Where is that button? There it is. Push the button, the screen comes on. Now I have to remember I do that in order to get to the login screen. But I have to remember, there's no obvious way to know. In the past, in the old fashioned computer, we open the computer, we turn it on, and [COUGH] there are menus. So if I go across the top and I click there, I see all sorts of possibilities. So, everything I need to know, everything I can possibly do, is listed. This is very strong, very high on discoverability. When we moved to tablets and we moved to gesture devices like this one, like this one, like this one, like this one, we lost that discoverability. And in some cases, we lost feedback. So why, and what can we do about it, and what are the principals of design that we should use in designing gestures? That's what this sequence, that's what this course, is about.