For questions specific to the Magisk systemless interface and its GUI application, Magisk Manager
Magisk is a systemless interface that developers can use to build custom mods for Android devices without touching
/system partition. It provides root access and a built-in hiding functionality (MagiskHide), and has a lot of modules available.
The name "Magisk" is created from the two words: it's a "Magic Mask" to Alter Android System Systemless-ly. To achieve that goal, Magisk patches the device's boot image.