If I have a patent. Does that mean it is illegal for others to use my idea?
Yes, the three exclusionary rights you get when you get a patent. Patent gives you the right to stop people from making it in the country where you have the patent, sell it in the country where you have the patent, or use it in the country where you have the patent. So long as the person is making, using, or selling something that’s covered by your patent as defined by the claims of the patent, then you have the right to say, “Stop, pay me some money.”
