Technically, this is not canning but it is about how to make your butter storable for an indefinite period of time.
Homesteading is all about making things last and about preparing for lean times. Of course, this is even more useful if you have a cow that you milk. Most of us don't, but sometimes it is better to not keep your freezer full of butter. I just went through an evacuation of my home town and had to throw away much of what I had in my refrigerator and freezer due the power being off for sometime between one and three days. It would have been great if I had some ghee store in my cupboard.
This is a really simple process.