Rigify - what are tweak bones,and what do they do? I am quite new in Blender, and try to understand  what are Tweak bones which are generated by Rigify.
How is using of them? Unfortunately, I could not find any clear definition of them.
Thanks a lot in advance!
They allow you to deform your character with a lot of freedom.
This can be useful for cartoony animation... although if you don't go too extreme with them, you could possibly use them to create realistic motion.
I have a video where I explain a bit about them:
https://www.youtube.com/watch?v=vKgH5zXIYmM&amp;feature=youtu.be&amp;t=1171