So here are the keyboard shortcuts for minimizing and maximizing a Window:
To minimize all the windows you can use the keyboard shortcut Windows Key + M or you can also use show desktop (Windows Key + D). I prefer the shortcut for show desktop as you can press it again to show the last active window.
To minimize only the active window, press alt + spacebar and then press N.
Sometimes when you open an application and if it opens by covering only half of the total window size and if you would like to maximize it, you can use the shortcut keys alt + spacebar and then X.
To close an active window, press alt + Spacebar and then C