Hello and thank you for your question.
In your head you have a groove in the skull and a rounded joint on the jaw, between these two bones that make of the temporal mandibular joint is a cartilage
disc. This disk is attached by muscles and elastic ligaments. when you open your jaw it rotates then slides down and forward, when this happens the disc slides back. When you close it goes back forward. Sometimes these ligaments become loose and there is a lag in the sliding of the disc.
A closing click arises during closing of the jaw and is caused by the condyle (the rounded part of your jaw joint) rapidly repositioning posteriorly (towards the back), displacing the disc anteriorly (towards the front) or medially (towards the side). An opening click arises in the opposite of what was just said.
If you get a line of 100 people 40-60 of these people will have clicking, cracking or popping in their jaws without any issues.
Hope this helps give you comfort.
Best wishes and good health