Minecraft wiki entry for Things_not_to_do, associated text: If the player has a flint and steel, they should not use fire charges to light casual fires. Fire charges require far more expensive materials to create than flint and steel and unlike flint and steel, each fire charge only has one use. Under normal circumstances, it is not worth wasting those hard-earned fire charges when the player could just use a flint and steel. However, if the player gets trapped in Nether without flint and steel, they can be useful for re-activating the portal, since all their ingredients appear naturally in Nether. (Gunpowder from ghasts, coal from wither skeletons and blaze powder from blaze rods obtained from blazes.) It can also be used for redstone contraptions, such as automatically lighting portals and ranged firebombs.