and what are they used for?
One is called "countersink" for large screws. All the others are call "burs". Use them as rasps in your drill motor.
Thank you Klem1! I inherited these from my father-in-law and never knew what they were used for. Seems like they are for carving wood. I don't do any wood carving, mostly shelves and boxes.
They are useful for making holes a bit larger.