What are Hot corners in macOS?
Hot Corners is a feature of macOS that lets you assign instant actions for when you move the mouse pointer to any one of the four corners of your Desktop.

Hot Corners can lead you to pretty powerful workflows using just the mouse cursor, such as:


Instantly showing/hiding the Dashboard.
Putting the display to sleep
Showing the Desktop
Displaying notifications by opening Notification Center
Showing/hiding the Launchpad
Showing/hiding the Mission Control.


The flexibility of doing these tasks without moving your hand from the mouse/trackpad can lead to faster and easier workflows.



Hot Corners can be configured by going to System Preferences app → Desktop &amp; Screen Saver → Hot Corners... or System Preferences app → Mission Control → Hot Corners....

For more details, go through the Macworld article, What’s hot about OS X’s Hot Corners.