One of the ways in which companies often trip up in their attempts to develop a patent portfolio is by selling a product, or even offering it for sale, before filing a patent application. If more than a year passes between the date of a sale or offer and the application filing date, the application is disqualified from receiving a patent. Likewise, if a sale or offer a year before the filing date is revealed only after the patent has been granted, the patent is declared invalid. In either case, the applicant is barred from obtaining a patent, and this is known as an “on-sale bar.”