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Priority date

Definition

The date that determines whether a piece of prior artprior artEarlier patents, publications, or products that existed before this patent's filing date. Patent claims must be novel over the prior art.Read more → counts against a patent application. In the US, the priority datepriority dateThe earliest date used to compare the patent against prior art. Usually equals the filing date.Read more → is typically the filing datefiling dateThe day the patent application was submitted to the USPTO. Sets the priority date for prior-art comparisons.Read more → of the earliest application in a patent familypatent familyA group of related patents covering the same invention in different countries or as continuations.Read more → to which the current application claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more → priority. Under the first-to-file system (post-AIA), the inventorinventorThe person who actually conceived the invention. Listed on the patent regardless of who owns it.Read more → with the earliest priority date wins if two people file on the same invention.

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Prior art

All publicly available information that existed before a patent's priority date that is relevant to the novelty and non-obviousness of the claimed invention. Prior art includes earlier patents, published patent applications, journal articles, product manuals, conference presentations, and anything that was publicly known or in use. Searching prior art before filing is one of the most valuable steps an inventor can take.

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Continuation-in-part (CIP)

A type of continuation that adds new subject matter to the original specification. The original claims keep the parent's priority date; the new material gets a new priority date. CIPs are commonly used when an inventor has improved or expanded an invention after the original filing. The different priority dates within a CIP can create complications during litigation.

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First-to-file

The rule, adopted in the U.S. by the America Invents Act, that when two people independently invent the same thing the patent goes to whoever filed first, not whoever invented first. It makes the filing date critical.

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Inventor

The person (or persons) who conceived the claimed invention. Inventorship is a legal concept distinct from contribution to a project — someone who merely built what was designed, or who had a general idea that was made more specific by someone else, may not qualify as an inventor. Incorrectly listing inventors can invalidate a patent.

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Patent

A government-granted right that gives an inventor the exclusive right to prevent others from making, using, selling, or importing a patented invention within the country that granted the patent, for a limited time. A patent does not give the owner the right to practice the invention — only the right to exclude others. The US issues three types: utility, design, and plant patents.

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Patent Cooperation Treaty (PCT)

An international treaty allowing inventors to file a single "PCT application" that preserves the right to seek patent protection in 150+ member countries. A PCT filing buys time — typically 30 months from the priority date — before the applicant must commit to specific national filings. It is not a "world patent"; each country still examines and grants its own patent under its own laws.

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