Few people know this, but your phone can launch any application if you tap its back.

If Android has one major advantage over the iPhone, it's its customization. Android phones like Samsung, Xiaomi, or Google Pixel have all sorts of little tricks and tips that allow for a multitude of uses.
This is the case with the technique we're going to discuss here. While some are already familiar with the "tap-to-back" feature, this isn't the case for all Android phone owners. When used properly, this option allows you to access certain applications or shortcuts very quickly, without touching your device's screen.

Tap-to-back, as its name suggests, is a tool found on several Android smartphones, such as the Google Pixel and Samsung. It allows you to configure shortcuts by tapping the back of the phone. Activating it, however, depends on the smartphone model you have.
If you have a Google Pixel, tap-to-back is easy to find in the phone's options. Open the Google Pixel's Settings app, then go to System > Gestures > Double-tap to launch actions . Then enable the option to configure the shortcut you want to use.
On Samsung phones, the feature is a bit more complicated to enable. You'll need two other official Samsung apps from the Galaxy Store: Good Lock and RegiStar . The latter can't be installed without the former, so proceed in this order: Open the Galaxy Store app on your device to search for and download Good Lock. Then launch Good Lock to find several apps for your Samsung. Download RegiStar and click on it to launch it. There, you'll find the "back-tap action" option to enable and configure to be able to use shortcuts by double or triple tapping the back of your device.
Xiaomi smartphones also have this feature if they are recent. To activate it, follow these steps: go to the " Settings" application > " Additional settings" > " Shortcuts to gestures" , Scroll down and tap "Back Tap" . Select the "Back Tap Double" or "Back Tap Triple" option to choose each of the associated shortcuts.
L'Internaute