A patent doesn't necessarily give you the right to manufacture or sell the product or design that you've patented, but allows you to prevent others from doing so. A company that spends millions in research and development costs is entitled to a period of exclusivity during which they can recoup those expenses. Any other company that attempts to market a product using the patented technology during this period is guilty of patent infringement. Damages awarded in patent infringement cases are usually substantial, and if it can be proven that the infringement was done with full knowledge of the existing patent, those damages can be tripled. A U-S patent can't prevent a company overseas from manufacturing a similar device or using your patented process. It can, however, be used to prevent the infringing company from marketing their products in this country. Even if you obtain a patent, that doesn't guarantee that you're not infringing on a previous patent. For this reason, it's often a good idea to seek experienced legal advice throughout the patent application process.