device tree in linux

Hi,
I'm working with am335x (BeagleBone Black has it), which has Linux Kernel OS on it.

part of configuring its GPIOs involves writing a device tree which sets the Mode of the PINs to 'GPIO' mode.

I googled device tree in ARM processors for a decent tutorial, also watched this Tutorial (Beaglebone: Introduction to GPIOs - Using Device Tree Overlay), but what i found wasn't a basic tutorial for beginners.

Could you please recommend on such tutorial that will bring me to the phase where I write my own device tree?

Are device trees used in the ARM's "industry" (i.e. companies use them when programming their ARM Linux Products?)

Thank you.

The tutorial is decent but it assumes you have a basic understanding of Linux kernel drivers and systems in general to be programming at that level.
To really understand the process there are no shortcuts for beginners. Linux system programming requires a lot of background study.
https://www.devicetree.org/Device_Tree_Usage