Eight-to-fourteen modulation (EFM) is a data encoding technique - formally, a line code - used by compact discs (CD), laserdiscs (LD) and pre-Hi-MD MiniDiscs. EFMPlus is a related code, used in DVDs and Super Audio CDs (SACDs).

EFM and EFMPlus were both invented by Kees A. Schouhamer Immink.