Everyone who feels adjusting or “cracking” their neck is good for them is wrong. This can become habit forming and add to the frequency of adjusting. If someone feels the need to do this, it indicates that there is an underlying problem. This habit can also increase your chances of having a stroke by making the neck hyper mobility.
The difference between a person doing it by themselves and a chiropractor is that the chiropractor is more specific at isolating the underlying cause. A good analogy is a kink in a chain, the kink represents a restricted vertebra and the link above or below are usually vertebra overcompensating by moving more than usual. The chiropractor can isolate that restriction and restore the natural mobility to the segment whereas a person doing a self-adjustment is nonspecific and gets a “crack” from usually the segment above or below. This can lead to instability and can stretch or tear the vertebral artery that runs through it.
But it feels so good!! Yes, I am sure it does but only for the short term. The noise that you hear is a release of synovial fluid gas. All joints have this gas in it. When you hear the noise it is just an indication that the joint has moved a certain degree. Along with the noise which I call a release or cavitation and not a “crack” is a release of endorphins which is your body’s natural pain killer. This is why it feels so good along with increased movement which is only temporarily because the underlying cause hasn’t been addressed.