216 Personal Content Experience: Managing Digital Life in the Mobile Age offer functionality, and the icons present objects graphically to the user. Pointing devices (such as a mouse, a pen, or a touch pad) use the direct manipulation interaction style, where the user can point and interact with the visible objects (such as icon or part of the UI) on the screen directly. Windows contain graphical elements known as UI compo- nents (widgets), which provide output based on the user’s input. The term desktop also refers to a metaphor, which attempts to mimic the real-world desktop, where windows represent documents on a table top. A benefi t of direct manipulation interaction is that it lets the user be in control (van Dam 1997; Myers 1996; Shneiderman 1998). In addition to direct manipulation, we distinguish other interaction styles that are highly relevant to mobile devices. The fi rst one is menu selection interaction style, which presents all the options available at any particular moment as a list of items and the user can then select the most appropriate one from the list. The benefi t of this interaction style is that it provides a clear structure that requires little learning as 6 long as the terminology does not get in the way. Form fi lling is an interaction style of choice when lots of data entry is required. Users can typically see all the related fi elds, navigate between them, and enter the data where required. However, the user must understand the purpose of the fi elds as well as valid input values. This makes form fi lling more suitable for intermediate users (Shneiderman 1998). The graphical WIMP user interfaces of today’s PCs should not be used in mobile devices as such. The visual representation and feed- back, as well as managing multiple windows, often demands a large display and requires a lot of the user’s attention that cannot be pro- vided by mobile devices in mobile use situations. In addition, mobile continuous use is diffi cult with a pointing device, since targeting at small icons requires accuracy that cannot be achieved easily while walking and using the device with one hand. 6.3.3 Interaction Technologies and Techniques To interact with the system, the mobile device provides input devices for the user to communicate their action and output devices that present the system’s state and feedback to the user. Often the mobile device is a single entity that contains all input and output devices. 6 It should be noted that menu selection refers to the main style of interaction with the device, whereas WIMP menus refer to user interface components used for provid- ing access to the system’s functionality and aid the main interaction method, which is direct manipulation.