A Practice Note discussing patent inventorship, including inventorship legal standards and determinations, the legal effects of inventorship, and correcting and challenging inventorship. This Note addresses conception, reduction to practice, joint inventorship, documenting inventions, drafting patent applications, and naming and correcting inventorship in patent applications and patents. This Note also includes overviews of derivation proceedings under 35 U.S.C. §§ 135 and 291, and inventorship correction actions under 35 U.S.C. § 256.