How does flint and steal make a spark?

Question: How does flint and steal make a spark?
- Keywords:
  fire,
  flint,
  spark
Asked by Zealousy to Rob on 19 Jun 2015.
- Rob Temperton answered on 19 Jun 2015:
  
  Not 100% certain of this so you may want to do some research and check my answer! Flint is a hard material. You rub it against iron and tiny bits of iron (from the steel) come off which burn in the air due to the heat (friction from hitting the flint and steel together).
  
  Rob

Question: How does flint and steal make a spark?