Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. An NSF (NES Sound Format) file is a sound data file containing instructions for the Nintendo Entertainment System (NES) sound hardware. It is akin to SID files from the Commodore. Many NSF files are prepared from the ROM images of commercial Nintendo games, containing the entire soundtracks and sometimes sound effects. Composers and hobbyists also use the NSF format to create new chiptune music from scratch. An NSF file is actually a modified NES ROM image with the game code, data, and graphics removed, leaving only the music engine and data. The files can be played on modern PCs using various plugins and standalone programs, including NES emulators.