Precisely what “post-PC” means for device markets is a bit subtle at times. Though some might argue the phrase will not be needed anymore, some might argue a better formulation is that post-PC means many of the activities people want to engage in will not require, and are not best suited to, a PC.

Another formulation might be that “PC” functions now overlap many other consumer devices. The obvious examples are a shift of activity from PCs to smartphones or tablets.

On the other hand, such diffusion of functionality and new consumer behaviors is bound to affect PC sales, because consumer demand now has shifted in the direction of tablets and smartphones. In short, what people now want to do, most of the time, is consume content and share short messages. Those activities conveniently can be executed on portable or mobile devices, most of the time.

Not surprisingly, most observers expect PC sales to slow, as a result. The worldwide PC market is expected to grow just 0.9 percent in 2012, according to International Data Corporation. That suggests 367 million PCs will ship in 2012, up just a fraction of a percent from 2011 and marking the second consecutive year of growth below two percent.

PC image via Shutterstock.com

Over the past couple of years, the regional pattern has been growing in emerging markets and the Asia-Pacific region with a sales decline in the United States, for example. What’s different in the later part of 2012 is that Asia-Pacific growth has slowed.

To be sure, there is a product refresh cycle coming, in the form of the new Windows 8 operating system, as well as economic distress. So IDC now expects worldwide PC shipment growth will average 7.1 percent from 2013 to 2016, down from the 8.4 percent compound annual growth rate previously forecast for that period.

"We expect the year will end with shipments in the U.S. falling by 3.7 percent, marking the second consecutive year of contraction,” said David Daoud, research director, Personal Computing at IDC.

The “post-PC” appellation probably means lots of things, among them a shift of consumer and business demand towards use of smartphones and tablets to accomplish tasks that once required a PC. That doesn’t mean an end to use of PCs for content creation and other work tasks. It’s just that the range of things people want to use appliances for has changed dramatically in the direction of content consumption as a primary activity.

Until relatively recently, that shift was disguised, as people did not have the range of devices available that clearly separate content creation from consumption.