The patent normally protects the invention only within the country that grants the patent. For instance, patents issued by the US Patent and Trademark Office excludes others from making, buying, or selling the invention only in the United States, and does not offer any protection in Europe or elsewhere.
For protection outside the “home" country, an inventor needs to either apply for patent in each country where he or she requires protection, or make an international application.
Each country has its own patent laws, which may contradict United States patent law. For instance, in most countries publication of the invention before applying for the patent bars the right to a patent, whereas the United States patent law allows applying for a patent within one year of the inventor publishing the invention. Some countries may void a patent on failure of the inventor to manufacture the product in that country within three years.
The Paris Convention for the Protection of Industrial Property, an international treaty signed by 168 countries provides the same rights to all applicants, regardless to nationality of the inventor. This treaty also allows deeming the date of the initial application in the inventors home country as the date of application in other countries, provided the application in other countries is made within the stipulated time period.
Another treaty, the Patent Cooperation Treaty, signed by 124 countries allows for international application through a centralized filing procedures and a standardized application format.