# Priority date

The date that determines whether a piece of prior art counts against a patent application. In the US, the priority date is typically the filing date of the earliest application in a patent family to which the current application claims priority. Under the first-to-file system (post-AIA), the inventor with the earliest priority date wins if two people file on the same invention.

**Full entry:** https://patentbrief.org/glossary/priority-date

**All patent terms:** https://patentbrief.org/glossary

---

_Source: PatentBrief — https://patentbrief.org. A plain-English glossary of US patent terms._