During a presentation you may want to start a video, or go to the next slide or maybe a run a different program. You can do all of the above and more with a click of a mouse; or maybe, you don't even need to click. You can just hover your mouse over the object and it will do what you ask it to do.
From the 'Action Settings' attach an action to a button or to an existing image in your slide and tell it what to do. It can even play a sound. It can be so versatile (just like you).