Have You Ever Heard Of This Type Of Egg?

While doing a little grocery shopping over the weekend I headed over to where the eggs are to grab some to color for our egg hunt, I came across these.

I had never noticed them before but this time they caught my eye. Cage free eggs. I cannot even begin to figure this one out! lol I took the picture and asked several friends and family members if they knew what the heck this was? No one had a clue, not even a guess. I can easily look it up but the fun is in finding out if anyone knows or has any suggestions? What the heck are 'cage free' eggs?