Recovery, in Android, refers to the bootable partition, in which the recovery console is installed.
It contains tools to help repair your installations as well as install official OS updates by using a combination of key presses or instructions from a command line sometimes.
Android is open, meaning the recovery source code is available, so that building a customized ROM is relatively easy.
1. First step in getting to recovery mode is turning off you device.
2. Then wait few seconds and press and hold power button with home button and volume down button together.
3. When the SAMSUNG logo appears on the screen, you can release the buttons.
4. After a moment of waiting your Galaxy S8 should boot into recovery mode.
5. And this is it! Now you know how to put your Samsung Galaxy S8 into Recovery Mode.
It's good to know also that you can boot directly into recovery mode and use it to factory reset the device, delete the cache partition, or apply software updates. It can help you fix your device.