Desktop gadgets was introduced in Windows 7 but removed from the subsequent Windows 8 and Windows 8.1.
I find desktop gadgets functionality pretty useful and handy in monitoring statuses and activities such as real time CPU usage, GPU usage, memory usage, network usage, hard disk usage, temperature readings, etc.
If you miss the fun of having desktop gadgets in Windows 8 / 8.1, you can get back that functionality by installing a 3rd party software called Windows Desktop Gadgets Revivied 2.0.
When it is up and running, you will get back the Gadgets option in Windows Desktop context menu and the Desktop Gadgets setting section in Control Panel's Appearance and Personalization. It behaves very similar to the desktop gadgets functionality in Windows 7. With it, you can now install those gadgets designed for Windows 7 into your Windows 8 / 8.1.