The Layers of paperless handsketching on a galaxy note

20 mins on a galaxy note, you can always revert back to where you started, save whatever you have drawn for use at a later date.

"LAYERS" IS THE MAGIC WORD TO KEEPING ALL YOUR UNUSED WORK, MODIFIED WORK, UNDO ANYTHING YOU HAVE DONE WRONGLY, OR REDO ANYTHING YOU HAVE UNDONE MISTAKABLY, the digital age which sometimes pampers us too much, we tend to take things for granted.

In real life, just be careful, every step we have TAKEN, CANNOT BE UNDONE, REDONE, OR SAVED UP FOR USE AT A LATER DATE. 
Digital data is only a supplement to what we are, what we do, and what we have.
NEVER TAKE LIFE FOR GRANTED