Although most inventions will be concerned with the rights a patent grants during its monopoly or in-force period (from the date the patent issues until it expires (20 years after the filing date)), the law actually recognizes five "rights" periods in the life of an invention. (1) Invention conceived but not yet documented: When an inventor conceives of an invention, but hasn't yet made any written, signed, dated, and witness record of it, the inventor has no legal rights whatsoever, only the potential for acquiring rights. (2) Invention documented but patent application not yet filed: After making a proper, signed, dated and witnessed documentation of an invention, the inventor has valuable rights against any inventor who later conceives of the same invention and applies for a patent. An inventor who documents the building and testing of the invention has substantially greater rights than one who merely documents conception. During this period the invention may also be treated as a "trade secret" this is, kept confidential. This gives the inventor the legal right to sue and recover damages against anyone who immorally learns of the invention, for instance, through industrial spying. (3) Patent Pending - Patent application filed but not yet issued: During the patent pending period, including the one year period after a provisional patent application is filed, the inventor's rights are the same as they are in period 2 above for the most part. Otherwise, the inventor has no rights whatsoever against infringers, only the hope of a future monopoly, which doesn't commence until a patent issues. Most companies that manufacture a product this is the subject of a pending patent application will mark the product "patent pending" in order to warn potential copiers that it they copy the product, they may have to stop later if and when the patent issues. The PTO by law must keep all patent applications preserved in secrecy until the application is published or the patent issues. The patent pending period usually lasts from one to three years. (4) In-force patent - patent issued but hasn't yet expired: After the patent issues, the patent owner can bring and maintain a lawsuit for a patent infringement against anyone who makes, uses or sells the invention without permission. The patents in force period last from the date it issues until 20 years from its filing date, provided maintenance fees are paid. Nearly every patent is guaranteed an in-force period of at least 17 years. In order to assure this 17-year term, the patent will be extended, if necessary, to compensate for delays resulting from failures by the PRO in processing the patent application. Also, once the patent issues, it becomes a public record or publication that can block others who file later from getting patents on the same or similar inventions, that is, it becomes "prior art" to anyone who files after its filing date. (5) Patent expired: After the patent expires (20 years after the filing date, or sooner if a maintenance fee isn't paid), the patent owner has no further rights, although infringement suits can be brought for any infringement that occurred during the patent's in-force period. An expired patent remains a valid "prior art reference" (as of its filing date) forever. IPStreet.com's patent search tools and resources will help you better understand if your idea is patentable, the duration of a patent and complex patent analytics.
In the U.S., the inventor has a "first to invent" claim which is different from other patenting organizations throughout the world who generally utilize "first to file." Debate over this issue, and which model best influences economic development is ongoing. Some are concerned that a change in patent rights may harm the small startup and benefit the incumbents with deeper pockets. You can read more about this topic.
In celebration of Noah Webster's Birthday (October 16, 2009), we have prepared an updated website. 
