The United States Patent and Trademark Office (USPTO) is one of the oldest patent offices in the world. The US adopted the first inventor to file provisions with the passing of the Leahy-Smith America Invents Act (AIA) on September 16, 2011. However, the USPTO offers a grace period of one year if the invention was disclosed publicly by the inventor themselves or by some other entity, with the authorization of the inventors, before the filing of the patent application.
The US patent statute, United States Code 35, and federal regulations, Code of Federal Regulations 37, include provisions for filing two kinds of patent applications, viz., 
1. Provisional Applications: The provisional applications are filed to obtain a filing number and a filing date on an incomplete invention, or for an invention whose economic significance and/or technical scope remains to be assessed.
2. Non-provisional Applications: The non-provisional applications may be filed as an extension of the provisional applications within a statutory period of twelve (12) months, extendible by another two (2) months under special circumstances. The non-provisional applications may also be directly filed as standalone applications without going through the provisional route, for inventions that ready for commercialization.