One of the biggest differences between desktop and mobile web applications is how we interact with an application. On a desktop or laptop computer, we have a keyboard and a mouse or trackpad, and we point and click or click and drag things. On mobile devices though, there is no keyboard and no mouse pointer. Instead, we use our fingers, and we do things like touch, drag, and tap. We can also do more complicated things, such as pinching two fingers together or rotating two fingers, and we usually expect this to do something in an application. In mapping applications on touch devices, for instance, we might expect that dragging a finger will pan the map and pinching two fingers will zoom in or out.
OpenLayers provides touch support for us in the form of interactions—recall that we talked about interactions in Chapter 8, Interacting with Your Map. The touch-specific interactions are as follows: