what causes heart burn? or what are all the things causing it?

empty stomach first and not even water would make worse and long term but then eating the things that cause burn and discomforts after this is the biggest problem that most people on earth have.

Heartburn has nothing to do with the heart obviously. Most often it is stomach acid flowing up past the lower esophageal sphincter into the esophagus that results in the burning sensation.

Acid from the stomach hits the esophagus. Maybe from a hiatal hernia.

Excess acid or pregnancy