Phones are essentially computers, and, like computers, get stuck or freeze once in a while. It's frustrating, especially if you don't know how to soft reset -- or restart -- your phone.
To soft reset a frozen Galaxy S8 or S8 Plus you need to hold the power button and the volume-down button for roughly 7 seconds.
Let go of the buttons once you feel the device vibrate and see the Samsung Galaxy S8 logo on the screen.
Your phone will then reboot, and hopefully, start working properly once again. Unfortunately, if you were working on something in an app, you'll likely lose your progress.
Here are some of our other Samsung Galaxy S8 tips: