The United States Patent and Trademark Office‘s Patent Application Information Retrieval system. Accessible over the Internet, PAIR displays information concerning patent applications including the full file wrapper of most patents filed after about 2001/2. PAIR has two sides, Public PAIR and Private PAIR.
Public PAIR allows ordinary members of the public to obtain information if they have a patent number or a patent application number; Private PAIR requires registration and the use of a password and allows a patent holder and its agents to view that status of pending unpublished patent applications and other data such as the payment of maintenance fees.
The European Patent Office maintains an analogous system, the European Patent Register.