Nobody has noticed until now, but sometime in the first months of 2013, the Linux desktop slipped into a new era. So far, though, the characteristics of that era have been haphazardly defined—when they have been defined at all.
Broadly speaking, the history of the Linux desktop can be divided into four main eras. The first might be called the Pre-Desktop era, in which many the command line was the interface of choice, and such graphical interfaces as were in use were window managers, which were limited in both usability and utilities. Symbolically, at least, it ended with the release of KDE 1.0 in July 1998.
Next came the GNOME-KDE era, in which these two desktops were so widely used on Linux that many users had barely heard of alternatives. During this era, both KDE and GNOME improved rapidly, overtaking Windows and OS X in features, although not always in polish or consistency.
The third era was ushered in by the release of KDE 4.0 in January 2008. Its first years were characterized by unrestrained innovation, as first KDE and then GNOME and Ubuntu produced their versions of the next-generation desktop environment. Since all three efforts were quickly met with negative reactions from users, I call this period the User Revolt era.
This third era weakened KDE's dominance and shattered GNOME's, as users looked for alternatives to the unpopular GNOME Shell. It also saw Ubuntu becoming increasingly isolated, as the rest of the free software community rejected its various attempts to assume leadership within the community.
Now, in the aftermath of the third area, a fourth era is starting to emerge. In many ways, any label seems premature because the era's priorities are still developing. So far, the most that can be said is that the era looks little like the three that came before‐aside, of course, from the obvious fact that it is determined by them.
So what are the characteristics of the new era? Four come to mind.
PC and Post-PC
In previous eras, the main distinctions among desktops were their size and speed. KDE and GNOME were inevitably described—exaggeratedly—as "bloated" by detractors, while lesser-known alternatives like Xfce tried to keep their memory footprint small and their operations fast.
However, during the user revolts, phones and tablets became the dominant computing devices, leading some to talk about the Post-PC era. GNOME and Ubuntu began to design as though the desktop were a mobile device's screen. However, this assumption may have been one of the reasons for the user revolts. Certainly, it was KDE, which had rearranged rather than altered the traditional desktop in its efforts to innovate, that recovered best from the revolts.
In the new era, the influence of mobile devices continues. However, the assumption that a single desktop environment fits all form factors seems to have been quietly discarded. By abstracting the interface from the rest of the desktop, KDE has made the development of different desktops for each device easier. Similarly, by accepting the idea of extensions, GNOME now allows users to remove as many of the elements of mobile design as they prefer.
Even Ubuntu, whose founder Mark Shuttleworth insisted on mobile-influenced designs in the Unity interface, has departed from it in practice when he came to design a phone. He now talks about "convergence"—the inter-operability of different form factors, rather than a common code base to display on every form factor.
In practice, the influence of mobile and desktop environments now seems more two-way than it did a few years ago. Besides Shuttleworth's talk about convergence with Ubuntu Edge, there is KDE's upcoming Vivaldi tablet, whose Plasma Active interface is informed by KDE's experiments with a variety of different interfaces. There is also Mozilla's FirefoxOS phone, an example of a desktop project rethinking itself for the mobile market.
Rather than the Post-PC era that was initially imagined, the new era seems likely to be characterized by a diversity of form factors more than the dominance of one type of hardware over the other. Already, the borrowing seems more two-way than everyone was imagining a year ago.
Desktop Diversity, Pro and Con
Where GNOME and KDE once accounted for over 85 percent of the desktop market, in the new era, Cinnamon, Mate, Unity, and Xfce also have generous shares of the market, as do as a sprinkling of smaller interfaces, such as LXDE and Razor-qt.
In readers' polls, KDE usually emerges as the single most widely used interface, but even it is outnumbered by those who use different interfaces built on the same underlying GNOME technology. This puts the GNOME project in the anomalous position of producing the utilities and applications that several interfaces use while its own GNOME Shell is reduced to one choice among many.
This situation means that user choice has never been so good as in the current era, especially for GNOME users. However, over the next few years, disadvantages may start to show in the difficulties of coordinating development.
Even in the GNOME and KDE era, such cooperation was often limited, with efforts like freedesktop.org eventually falling semi-moribund. If two have difficulties continuing cross-compatibility, six might find coordination next to impossible—especially when at least one (Unity) shows little interest in cooperating with others unless it can be in charge.