IBM in the mainframe era; Digital Equipment Corp. in the mini-computer era and Microsoft and Intel in the PC (or Cisco in the client-server era, as one might also refer to the PC era) are examples.
But here's the thing: we don't yet know whether the new era is here, or only coming. There has been a trend towards computing pervasiveness, as each era has succeeded the earlier era. Computing used to be in a "glass room." Then it could be done in a closet. With PCs computing moved to the desktop.
Certainly computing in a mobile period (we can't say yet whether it is a "mobile era") is moving beyond the desktop and into pockets and purses. We already can predict that computing has begun to become pervasive in all sorts of machinery as well.
Nor is is easy to describe even the present era. The role of software obviously has become more important over time. But, to this point, computing eras have never been defined by the key applications enabled. Perhaps we will one day see matters differently, but it would be a change to shift from "how" computing is done to "what computing does" to define the eras.
The Internet is more important, but not necessarily always because that is where the "computing" is done. Cloud computing is becoming more important, and does shift the locus of computing activities.
We all sense that a new era is coming, and that the Internet, mobile devices and applications will be more important. But there is not any agreement on whether we have "arrived" or are still only approaching the new era.
Most would agree that a new era--one we cannot yet even name--is coming. Most think the Internet and mobile devices will have something to do with that new era, but we can't be completely sure yet whether that is the right way to look at what is coming.
But there are signs. Apple's market capitalization topped $500 billion for the first time in February 2012. Apple's valuation is notable in other ways as well.
Apple is in a class by itself, both financially and in terms of its leadership of the technology industry. In some ways, that is a return to the older pattern, where IBM made computers, as did DEC. In the PC era, neither Microsoft nor Intel did so.
That isn't to say Apple is now the dominant firm in tomorrow's era, but simply to note that, if there are epochs within eras, then right now Apple best exemplifies leadership of computing. Paradoxically, Apple has dropped the word "Computer" from its name, which further indicates change.
We certainly are leaving the PC era. That's why former Apple CEO Steve Jobs always insisted the iPad was not a PC. In fact, many would insist that it is the tablet's optimization for content consumption that makes it distinctive.
We can't yet say that the next era of computing is defined by mobile devices, tablets, the Internet or cloud computing or even the fact that leadership is shifting more in the direction of applications and activities than computing appliances. But all of that hints at the shape of what might be coming.
But there are other signs. Google is the first really-big technology company with an advertising revenue model. In the past, it has been software or hardware sales that were the revenue driver.
Nor is it so easy to clearly separate dominant firms that are built on the existence of the Internet (which might be an epoch within the PC era, or a name for the next era, or a way of creating and using applications that could span eras) from the actual era itself.
Some might say that among the changes is that the mode of computing matters less than the applications enabled by computing. Though "a machine" has been the exemplar of past computing eras, maybe that will not be the case next time, or in eras to follow. Perhaps something else will be the defining element.
It would be reasonable to say that, although the PC is the dominant device, mobile phones and tablets are being added to the device mix. Nor would it be incorrect to say that the Internet has become the key network used by all the devices.
But neither is it easy to sort out the relationship between Internet as network, devices and applications. People do all sorts of things on the Internet, but it wouldn't make sense to say we are in the era of Internet-enabled shopping, searching, viewing, listening, game playing or communicating. We do all those things, and more, but the activities themselves do not seem to make sense as a way of describing the era.
Consider that Amazon and Barnes & Noble now appear on rankings of tablet market share, for example. That itself hints at a shift. And Apple is something of an anomaly. Though it began life in the PC era, it never "lead" that era. Only now, as it has dropped the word "computer" from its name, and only as devices other than computers have driven its business (iPods), and now drive its business (mobile phones, tablets), has Apple become perhaps the dominant force in "computing." It's a paradox.
In the fourth quarter of 2011, S&P 500 firms grew earnings 6.6 percent. But remove only Apple from the index and S&P 500 and the index grew at only a 2.8 percent rate. In other words, Apple performs so much better than most other firms that it distorts perceptions of the market.
Also, some would note, Apple, in terms of market valuation is bigger than that of Google and Microsoft combined. Microsoft is valued at about $257 billion and Google at about $197 billion.
In the product area, though many firms "compete" against Apple, few can approach it. In very real terms, there is not yet so much a "tablet" market as there is an "iPad" market, as Apple holds a 62-percent share of unit sales.
In smart phones, the story is not so much unit shipments as profit. In the third quarter of 2011 Apple earned about 61 percent of total smart phone profits, globally, all by itself.
Although soaring sales of Amazon’s Kindle Fire and other low-priced tablets trimmed Apple Inc.’s media tablet market share in the fourth-quarter, it was Apple’s own newly introduced iPhone 4S that proved to be the strongest competitor for the iPad during the final three months of 2011.
In other words, Apple's biggest competition, in some ways, is itself.
Perhaps the reason for our current perplexity is that, in the future, we won't be able to define eras by devices at all. That itself would be a huge change.