Remove screw? How do I remove screws that are not a flat head or...

How do I remove screws that are not a flat head or a philips manager? They have a flat round end to them and instead of a cross (for philips ) or a flat cranium shape its a complete circle I have a screw driver that fits the screws but it wont loosen the screw at all!
House design?
is it a cap screw? after u need an allen key wrench to loosen it, gain a set and place the right size in and loosen.
Am I using the oven right?
Spray the screws next to WD40 or a similar product, leave for 1/2 hour and they should come out if you have the correct screw driver

Bath or shower?
hold you tried drilling them out.
as someone has suggested if the hole is round nothing will transport it out and it's probably a rivet. a drill should work on a rivet. Is is a true circle or a hex screw. If it's a hex screw you will need a hex screwdriver. If its really round then nought will work since the screwdriver will just spin around.
What's another word for wood burning art?
Answers:    think it sounds close to a rivet. won't come out with a 'driver', it has no threads.