What are hiccups? What are hiccups?How are they generated and are they involuntary?Does it happen when we eat something tart?Or is there any other cause?I tried to find the solution but I always got different answers

It is essentially the phrenic nerve being irritated and as such the diaphragm (innervated by the phrenic nerve) contracts when involuntary signals are generated as a result of the irritation.

This irritation can occur for a variety of reasons.