This is not going to be a "this format is better than...". It's simply going to clear up a few misconceptions bandied about on this forum regarding the jpg file format. In fact, it's only going to clear up one misconception about this file format. The jpg format is a lossy file format. This means it is going to lose data. An understanding of discrete cosine transforms would be helpful in understanding the process. However, suffice it to say, here's what this post is going to clear up.

If one opens a jpg file, looks at it, and closes it, nothing happens to the file.

If one opens a jpg file, looks at it, and saves it, it degrades.

This is just the nature of the jpg file format and the save algorithm. It's that simple. Open, Look, Close, nothing. Open, Look, Save, file changes.

Yes, one can edit a jpg. However, in addition to the edits one makes, the save process works just the same making additional changes to the file over which the photographer has no control. The only control the photographer has is how much more gets changed based on the amount of compression selected at the time of saving the file.

If you don't believe this, it's simple to prove. Using the diff function in UNIX, or the free Windows program windiff will show you the changes. Can you visually see them, perhaps yes, perhaps no. The changes are there none the less. Again, it requires nothing more than a Save to instigate a change to the file.
--Bob

This is all fascinating and I want to state that I am stuck with Apple's iCloud. The choice I have is the bottom level 27 inch iMac = $1799.00; I only want to edit photos, not videos, at this time. I back-up my (4+ year old) MacBook Pro onto an external "PassPort" drive, and it doesn't backup my documents or photos currently on their stupid cloud. I brought my older MacBook Air to the genius bar at the Boylston Street Apple store in Boston about a month ago, and they were no help. I couldn't seem to get thru to them that I WANT a backup of my documents/pictures/videos on a hard drive LOCALLY, besides their iCloud. It's like I was speaking a different language. I just don't think I can get 27 inches high resolution display, PC computer for less then $1,800.00??? Can I or not? Thanks.

Although I am in fact retired and living on a fixed income, I CAN afford the $10/mo for LR-PS now. But I have decided NOT to get on the subscription boat because of concerns about what can happen down the road. I am somewhat concerned that the monthly subscription amount will go up in the future, perhaps substantially. And IF the monthly fee goes up at a time when I CAN'T afford to keep on paying it, I would essentially be locked out of all the adjustments I make in LR from now until then. I would have to figure out what software to switch to and how to get my images moved in the most usable form, perhaps in a short time frame.

By sticking with my standalone LR6, and PS Elements (which does all the pixel level adjustments I actually need), I retain full control/use of my images as long as LR6 will run on one of my computers. I can keep an eye on LR substitutes as they come along, and decide when and how to switch to one (or more) should that prove desirable and feasible down the road. Hopefully, there would be little time pressure to actually complete the move, as well as a mass of experience from others who have made the same switch already and can speak knowledgeably of the benefits and pitfalls.