A student in a recent class shared the following story. I'm repeating from memory.
When I was 14 I was out shooting one time with a few friends. Without asking, we had borrowed my father's .22 pistol. At one point my friend pulled the trigger back and nothing happened. He wasn't sure if it was out of ammunition or if something else was wrong but after a moment we dismissed it and he handed the gun to me.
At this point we sat down at a bench and as I examined the firearm it discharged without me touching the trigger. The discharged bullet struck my friend in the belly. I've been scared of firearms ever since. My friend still has health complications to this day.
A hang fire takes place when there is a delay from when the firing pin strikes the round and the powder ignites and discharges the bullet from the shell casing. Hang fires are fairly uncommon and even when they do occur the delay between the trigger and the shot being fired is generally small… a few seconds at most. On these rare ocassions when the hang fire may be 10+ seconds serious accidents often occur as the shooter has dismissed the incident and has stopped taking care for where the firearm is pointed and how it is being handled.
This particular tale is tragic as the brother who was fired upon sustained some serious injuries that took time and a hospital to recover from. Emotionally it was also difficult on both sides to deal with and only with a great deal of time has a recovery taken place.
Take care. Firearms and ammunition are not perfect and knowing how to deal with their imperfections is part of developing your safety skills.