The expressions "patent pending" (sometimes abbreviated by "pat. pend." or "pat. pending") or "patent applied for" refer to a warning that inventors are entitled to use in reference to their product once a patent application has been filed, but prior to the patent being issued. The marking serves to notify potential infringers who would copy the invention that they may be liable for damages once a patent is issued. Fraudulent use of the patent pending warning is prohibited by United States law and inventors should be cautious when marking products or methods that may arguably not be covered by any pending patent application.