Evolution of the clock icon
Ever since the first modern computer was developed, the manufacturers gave one of the most basic functional icons: the clock. The clock was very useful, especially if you consider the fact that the first computers were used for anything but entertainment. Back in the 80s, computers were very basic. They ran on an MSDos format which displayed the time, but in a digital formal, not with icons. Computer icons first came into existence with the advent of Windows 1.0x in November 20, 1985. The clock icon has always been very useful during work. The operators could keep track of time easily.
The first clock image was very simple. Windows 1.0x sported an analog clock picture which was professional enough. Though simple, it did its job.

In the Windows 2 series, the clock icon was more compact.

Windows 3 saw a more sophisticated interface. Additionally, this version clearly indicated choices to minimize and maximize the Clock tab.

The OS/2 which was developed by IBM in 1987 had the very first 3D operating interface. Its system clock icon reflected it well.

With the advent of Windows 95 in 1987, many icons were developed which we know even now. Most icons we use were from this time period.

In Window 10, its latest version marketed, the clock icon has reached its greatest level of perfection, beauty and utility.
