As others have said, I use it mainly for the search function to start programs as well as many shortcuts. I’ve seen others mention screenshots and locking, but here are a few more:
Win+. - Opens the special symbols/emoji windows
Win+ left or right arrow - Snaps a window to the left or right half of the screen, respectively. Up arrow maximizes, down minimizes.
Win+r - Opens the run dialog
Win+v - Opens clipboard history (history is off by default, it will ask you to enable it the first time you use the shortcut)
Win+x - Opens the ‘quick link’ menu (Power Options, Event Viewer, System, Device Manager, Network Connections, Disk Management, Computer Management, and Command Prompts
As a bonus, my favorite windows shortcut is Ctrl+Win+Alt+Shift+L, which opens linkedin in in a new browser tab.
As others have said, I use it mainly for the search function to start programs as well as many shortcuts. I’ve seen others mention screenshots and locking, but here are a few more:
A full list can be found here: windows key shortcuts