Cracking your back is generally not dangerous as long as you do it cautiously and gently. Some rare instances have been known to hurt the spine or nerves due to aggressive cracking and jerking that are not natural.
Most individuals crack their backs by stretching or twisting, in which cases the crack is unavoidable.
Some people argue that cracking your joints causes arthritis, but there is no medical evidence to support that claim.
Now even though back cracking is not dangerous, that doesn't mean it is normal or recommended as a healing technique.
If you have the need to crack your back daily, we always recommend seeking chiropractic care to treat the issue at its source.
This is because some individuals that force their back to crack too often cause more significant pain and discomfort to the area.
You must remember that your spinal discs, cartilage, and nerves are fragile and delicate and should only be treated by a chiropractor who is a professional in performing manual adjustments.
So although it feels good to crack your back, always be gentle and avoid any type of force.
However, when it comes to adjusting your spinal column, leave this job to the professionals and schedule an appointment with a chiropractor.  You do not want to cause yourself permanent damage and pain by causing one of the discs in your back to slip or herniate.