First-to-File

The rule by which patent offices determine entitlement to a patent for an invention in the case that an invention is independently created by different inventors.  Specifically, the first inventor to file a patent application for an invention is entitled to the patent for that invention whilst anyone who files a patent application for that same invention subsequently will not be entitled to a patent for that same invention.  Historically, some patent offices (notably the US) used a first-to-invent rule to determine entitlement.  However, this approach has now been phased out for new applications.