Willgoy,
Firesteels, or ferro rods are actually what are known as ferrocerium or "mish metal" rods. Thaey ares sometimes erroneously called metal matches or flints.
Here is a pretty helpful write-up. Do a search on this forum for firesteel, ferro rod or tinder and you will have a wealth of information to absorb. Esssentially, a ferro rod is a man-made metal rod used to start fires by scraping (not striking) it with a hard, sharp object. This causes a shower of sparks to fall which are directed onto suitable tinder, which will catch fire, igniting kindling, and eventually your main fuel wood.
These rods sometimes are attached to a handle to make them more comfortable to use. Sometimes that handle is magnesium or "fatwood" (another good term to look up) is used as a handle material so that tinder is always available. The rods range in size from a tiny 1/8" by 2" to 1/2" by 5". Popular models include the
Swedish Firesteel, the
BSA Hot Spark, and the ever maligned,
Doan Magnesium Firestarter.
The job of the tinder is to catch the spark and nurse it into a flame hot enough to ignite the next stage of fuel/tinder. When you are first starting out learning to make fires this way, feel free to use prepared tinders such as fine steel wool, cotton balls (often enhanced by soaking them in petrolium jelly), dryer lint, or wax paper. Once you've got the hang of it, start working on finding natural items in the field that will work as tinder.
I carry lighters and matches with me when out camping, but usually use a ferro rod to start fires just for the practice. There are tons of good threads on here about firestarting and a bunch of guys that are very experienced.
Sorry I went on for so long. I hope this helps.
-- FLIX