24 Personal Content Experience: Managing Digital Life in the Mobile Age PDAs normally do not include keyboards, most users have to stop moving in order to do anything with their devices. PDAs include most functions found in PCs, but the most popular application appears to relate to PIM: calendars, phonebooks, short notes, voice memos. Many people also do e-mail and Web browsing on PDAs, at least when the connections allow. Mobile music, games, navigation, translation, and e-books are also commonly used. There are a rich variety of content types that can be viewed and edited on PDAs, and the UI limitations only seem to exclude most graphically or computationally extensive applications. Previously, network connectivity relied on synchronization of PDA data with net- worked sources while docked at a home base, but nowadays many devices have wireless connectivity features (WLAN, 3G) and the bound- ary between smart phones and PDAs has started to blur. 2.2.3.4 Smart Phones Mobile phones were traditionally designed for communication, primar- ily for talking, but later also for messaging via SMS, instant messages, and e-mail. Modern smart phones include the same PIM functions as found in PDAs, and there are a variety of specialized phone designs for imaging, gaming, fashion, and sports. The most fundamental factor that differentiates phones from common PDAs is their connectedness via cellular data channels. Mobile phones are (potentially) always on, always connected even on the move. While phones are not yet true Internet citizens, the limitations are more economical than technical. The interaction with mobile phones is not much different to that with PDAs, although phones typically shun pointing devices and favour keyboards that are more usable while walking or driving (not that we advise doing so!). With integrated cameras and music players, modern smart phones now treat images, videos, and music as everyday mobile data types. 2.2.4 Accessories and Other Devices The three categories described above may have many accessories. Here we divide them into the following categories based on their purpose: • Improving mobility. For example, a headset for hands-free voice communication; extending use with high capacity batteries or travel chargers for car lighter or USB port; enhancing wearability or carryability with belt cases, pouches, straps, and armbands;