This is a quick tip I stumbled upon while randomly messing around with my Mac. It is to do with hiding applications / windows on your Mac. Normally if you press Command + H with the current application open it will hide the windows for that app. However this can also be achieved if you press alt (or option key if you prefer to call it that) and click the dock icon of the app you want to hide. In the blink of an eye your Mac will hide every window for that selected application. This tip can also be extended if you press alt and select a different application. This will hide the application windows you are currently using and switch to the dock app you just selected.
I find this useful if I have temporarily finished with an app and want to switch to something else. I hold down alt key and click my next app. The previous app windows are hidden and will only re-appear if I want to use the application again.
This tip can also be extended to hide every window on your screen. Press and hold alt and option, then click the dock icon for the current app. This will hide every other window on the screen other than the application you have just selected. This is useful if you want to clear your workspace and don’t want to close apps or manually hide every window. In a similar method to just holding the alt key. If you press alt and command at the same time and select a different application, it will hide every window except the app you are switching to.
On a side note, if you right click on a dock icon and press alt you get a couple of different options from the pop up menu. Such as Hide Others and Force Quit.
Just a quick tip for Sunday afternoon. I found it quite useful. If you want to extend your learning about your Mac I recommend you read the tips or tricks section of this site or read, Mac: The Missing Manual, if you want tips in a book like format.