Along with the monumental updates that Apple gives its Mac lineup every year, they also put a lot of focus on gesture control on their PC and laptop lineup. The magic trackpad that is available by default on the Macbook and as a peripheral for the Mac, supports a host of gesture-based controls, that makes it super easy to use the Mac device and also adds in some much-needed functionalities into the device.
Initially, the Mac trackpad allowed you to swipe up and down to scroll through a page, scroll sideways to change the page on a website or E-book, but when Apple saw that most other competing laptops had introduced these gestures, they went a step ahead and introduced a whole new array of gestures that took the Apple PCs to a whole new level. One such gesture is the three-finger swipe.
When you swipe up on the Mac trackpad with three fingers, it opens the background apps window. This basically shows you all the apps that are open on your Mac/Macbook at that moment. You can now click on any of the apps to open them.
