Recent developments have seen the widespread proliferation of both large public displays and small personal display technologies. In parallel, novel forms of human–computer interaction such as multi-touch technology have transformed these devices from passive displays into interactive systems. Examples of such small displays include PDAs, Tablets and iPhones while examples of large interactive surfaces (multi-touch driven displays) include the Diamondtouch and Microsoft Surface. With these, users can now interact directly with the displayed objects by simply touching the display, creating a sense of immediacy and natural interaction. This sense of immediacy gives rise to a range of human–computer interactions along with support for multi-device or public display collaborative activities.