What do we mean "mobile device"?

It's pretty clear that mobile devices ... hang on a sec.  What's a mobile device?  According to Wikipedia, it's, um, a small electronic device you can carry around.  But not a laptop.  So a smart phone, a not-so-smart phone, a tablet computer, a camera, an MP3 player, a handheld video game, a pager ...

A few of those have been around a long time, at least by electronic standards.  Somehow, I don't think that most people have devices like this in mind when they speak of mobile devices.  For practical purposes, "mobile devices" means "smart phones, tablets and stuff like that".  More precisely, it's not just mobility that people care about.  It's mobile connectivity, the idea that your mobile device can connect to the world at large and interact with it in arbitrary ways.  The mobile web, that is.

So where was I?

It's pretty clear that mobile devices are playing a bigger and bigger role in people's lives these days.  Lots and lots and lots of people have cell phones, quite a few people have tablets, and more and more do every day(*).  It's also clear that people have adapted to having ready access to the web.  One sure way to know you're out in the boonies, whether for the good of getting away from it all or the ill of being cut off from it all, is not having any bars.

When I was a kid, not that long ago, I like to think, if you wanted to meet someone at a large public place, you would have to pre-arrange -- "Meet me on the west side of the station near the stairs for the subway line."  Now you can just call up your party and ask "Um, hey, where are you? ... oh, there I see you."  If you broke down at the side of the interstate, you'd have to wait for someone come by (unless you had a CB, and a lot of people did, though not necessarily for that particular reason).  Now you just call someone.  And, of course, all the behavioral changes brought on by the web, like pulling down news you're interested in instead of waiting for the evening paper or news broadcast, are possible whether or not you happen to be near home.

So if a mobile device is something mobile that can hook you up to the web, then what we have is a series of less-tethered-to-a-particular-place ways of connecting:

• Ancient times:  If you could connect to a remote system at all, it was through work, or a university or other such institution.  Maybe you could dial in to that system from home, using a honking big dumb terminal.  One way or another you were essentially going over phone lines (even the backbone of the time was a bunch of T1 lines, if I understand correctly).
• BBSs (Bulletin Board Systems) and online services such as Compu$erve begin to appear and personal computers with modems become commercially available.  Now you can connect from home, generally to a world completely different from what you'd encounter at work, assuming your line of work even involved the internet.
• Laptops become widespread.  Now you can connect from anywhere you can lug your laptop, assuming you can tie up a phone line.  By this time you can also plug your laptop in to people's local networks.  Cell phones exist, but using them to connect to the internet is cumbersome at best, and almost certainly very expensive.  Internet cafes pop up.
• WiFi becomes widespread.  With municipalities airports, hotels and commercial chains putting up hotspots here and there, the concept of an "internet cafe" becomes somewhat moot.  Many people can connect from wherever they are much of the time.  Phones are becoming webbier, but in a limited way.
• Present day: Smart phones become widespread.  Apps are developed so that you can interact with your favorite sites without squinting at a web site through a browser.  Phones have enough horsepower to provide a nice, snappy experience, at least where you have coverage.

If mobile connectivity is more important than whether a device will fit in your shirt pocket, and I think in this context it is, then mobility starts somewhere around the spread of laptops.  Certainly by the time WiFi is widespread and home "broadband" access is commercially available, the difference from the present day is more degree than kind (understanding that a big enough difference in degree is essentially a difference in kind).

That's not to say we're not entering a new phase.  We are.  A location-aware phone that is always on and always with you is significantly different from a laptop you have to plug in, power on, log in, etc.  From a technical point of view, designing for a small touch screen is significantly different from a laptop screen, much less a 30" monitor.  Nonetheless, the current phase is just the latest in a series of steps making it easier and easier to connect from anywhere.

(*) It's not always clear what "lots of people" or "widespread" should mean.  Widespread among affluent technophiles?  Lots of people in the developed world?  Widespread in a large portion of the world -- which may be ahead of parts of the developed world when it comes to mobile communication?  I'm bravely sidestepping such questions here, but I wanted to at least call them out.