Unless you do design for something totally unambiguous like mobile phone OSs, you might has "what do you mean by mobile?" And the answer is, well, kind of a broad range of things, and not a very quick answer.

While other portable devices pre-date modern mobile telephony (both the Gameboy and the GPS network are earlier than GSM), mobile phones have evolved fastest, absorbed other technologies and form a useful core technology to consider all others. The evolution of mobile can be considered as:

  1. Voice
  2. Paging and Text
  3. Pervasive network connectivity
  4. General computing devices

If you consider a current mobile phone as a generally 4th era device instead, what you find is they are:

If we use this definition, then pretty much all mobile phones are included.

And some other devices in the "MID" (mobile internet device) range, such as the iPod Touch and the recent spate of mobile tablets. So, "mobile" is also:

But my device feels mobile also

But what if you are one of those folks who glues an iPad to down, to make it an ad hoc kiosk? It's no longer small, it's not portable anymore, so what is it?

Well, obviously it's a mobile device still. And if so, then the gut feeling is that so are GPS receivers, portable game systems, maybe even TV game systems. And then why not DVRs, and so on.

But certainly not TV video programming. And there are Windows tablets hardly bigger than many of the new iOS and Android tablets, which are clearly not particularly mobile-like, even if some of them are used on small screens, and in unusual environments.

So what makes some "mobile" and some just "not"? From a broader point of view, without as much focus on the hardware but the interaction and method of use, it seems to be:

Take a Windows tablet PC, for example. It has pen input, but spottily implemented; text entry works well, but other controls are still in desktop-PC mode, so are hard to use. Many have GPS, cameras, audio input or even accelerometers. But they are not integrated with the OS, or the general user interaction; special software is required to use them, and in general the device doesn't know which way you are facing, where you are, or even react to whether it is day or night.

So, simply making a device small, connected and battery powered doesn't make it mobile because its not contextually-ware or naturally-interactive.

Consider the Wii, or X-Box Kinect instead. Though the display is not at all portable, they are at their core aware of user position, they change with the type of input being used, and the entire interface has been designed to support interaction via a game controller, or simply waving your arms at the screen. These meet the interactive criteria to be a "mobile" device.

The "constrained interface" bullet above might seem to be there just so we can arbitrarily say "mobile is small." However, it's as organically derived from user behaviors with these devices as the other bullets are. For example, if you put a real, full-size keyboard on a mobile device, the keyboard acts like a desktop computer, and suddenly all text input follows desktop computing patterns, not mobile patterns. The method by which the user interacts is the guiding principle in this defintion.

So, while this book does still focus on the classic answer, the mobile phone and especially the smartphone, similar interactions from kiosks to game stations to telematics, are also considered. In some cases, these may even be referred to in the pattern language.

So, which kind of devices are these?

In the end, a lot of devices have at least some of these attributes, and their design can be informed by mobile patterns. The ubiquity of mobiles also may mean that employing these as universal patterns is a good thing, as users may require less training when using interfaces to which they are accustomed.

A non-inclusive list of device and use categories that were considered during writing, or which are specifically mentioned in the book are:

Aside from the logical reasoning outlined above, we have worked on many of these categories of products -- at least a little -- and have had good results applying these principles to the design of interfaces for these devices.

So, what patterns are covered here?

These are patterns for interaction design on these devices. To that end, they expand to talk about buttons, accelerometers, cameras, lights and other hardware facets. But all within the context of on-screen interaction design. Or, the equivalent of "on-screen" for audio, annunciator lights, and haptics.

Likewise, these focus on behaviors that can be changed, so mostly address generalized interactive elements that can be used for applications and websites. Keyboard design, dialers and other parts of the interface that are only changeable by manufacturers or operators (or certain hacking shops) are included as well.

These are included mostly for understanding, so every designer working on their small part has an idea what the immutable components are for, and how they should work. But also because there are a lot of handsets being designed, there are a lot of operators and the growth should mean more and more room for these devices to be designed and configured in the future.

Next: What is a Pattern?